Friction agitation joining method method for manufacturing joined butted members and friction agitation joining apparatus

ABSTRACT

In the friction agitation joining method according to the present invention, two plate-shaped joining members different in thickness, or a first joining member ( 1 ) and a second joining member ( 2 ), are butted against each other with a level difference formed at upper surface sides thereof. A rotating probe ( 42 ) of the joining tool ( 40 ) is inserted into the butted portion ( 3 ) of said first and second joining members ( 1,2 ) from the upper surface sides thereof. Joining-direction front sides of the first joining member ( 1 ) and the second joining member ( 2 ) with respect to the probe inserted position is pressed by a first front pressing roller ( 11 ) and a second front pressing roller ( 11 ), respectively, from the upper surface sides thereof. Furthermore, joining-direction lower sides of the first joining member ( 1 ) and the second joining member ( 2 ) with respect to a probe inserted position from said upper surface sides is pressed by a first lower pressing roller ( 21 ) and a second lower pressing roller ( 22 ), respectively, from the upper surface sides thereof. In this state, the butted portion ( 3 ) is joined by the friction agitation joining method.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent ApplicationsNos. 2001-63267 and 2001-63293 each filed on Mar. 7, 2001, and U.S.Provisional Applications Nos.60/303,146 and 60/303,158 each filed onJul. 6, 2001 the disclosure of which is incorporated by reference in itsentirety.

[0002] This application is an application filed under 35 U.S.C. §111(a)claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing dataof Provisional Applications Nos.60/303,146 and 60/303,158 each filed onJul. 6, 2001 pursuant to 35 U.S.C. §111(b).

TECHNICAL FIELD

[0003] The present invention relates to a friction agitation joiningmethod, a method for manufacturing joined butted members and a frictionagitation joining apparatus preferably used for manufacturing metalplate-shaped members used as, for example, flooring materials, wallmaterials and ceiling materials for transporting device such asautomobiles, aircrafts and railroad vehicles.

BACKGROUND ART

[0004] A friction agitation joining method belongs to a category of asolid state welding method. The friction agitation joining method hassuch advantages that it can be applied to various metal joining membersregardless of the materials and that joining members are hardly deformedby thermal strains at the time of joining. Thus, in recent years, themethod has been used for joining various structural members.

[0005] This friction agitation joining method will be explained withreference to FIGS. 29 to 31. In these figures, the reference numeral 101denotes a long and thin plate-shaped metal first joining member, and 102denotes a long and thick plate-shaped metal second joining member. Thesejoining members 101 and 102 are butted against each other at thewidthwise sides thereof with the lower surfaces being flush with eachother (the reference numeral 103 denotes the butted portion). Thus, thelevel difference corresponding to the thickness difference is formed atthe surface side thereof. In this butted state, these joining members101 and 102 are supported from the lower surface sides thereof by theforward and backward supporting rollers 131 and 132. The referencenumeral 104 denotes a stepped portion formed at the surface side of thejoining members 101 and 102.

[0006] The reference numeral 140 denotes a joining tool for performing afriction agitation joining method. This joining tool 140 is equippedwith a columnar rotor 141 having a larger diameter and a pin-shapedprobe 142 having a smaller diameter integrally protruded from therotational center of the end surface of the rotor 141 and extendingalong the rotation axis Q′.

[0007] The reference numeral 133 denotes a backing roller. This backingroller 133 is disposed at the lower surface side of the joining members101 and 102 opposite to the probe 142 of the joining tool 140.

[0008] When joining the butted portion 103 of the joining members 101and 102 using the friction agitation joining tool 140, first, therotating probe 142 of the joining tool 140 is inserted into the buttedportion 103 of the joining members 101 and 102 from the upper sidethereof. Then, in this inserted state, both the joining members 101 and102 are moved in a longitudinal direction thereof with the probeinserted in the butted portion 103 so that the probe 142 advances alongthe butted portion 103. “MD′” denotes the moving direction of both thejoining members 101 and 102. In accordance with the movement of both thejoining members 101 and 102, the butted portion 103 of both the joiningmembers 101 and 102 is joined by the probe 142 at the probe insertedposition. The reference numeral 103′ denotes a joined (i.e., welded)butted portion of the joining members 101 and 102. “W′” denotes a joinedportion formed at the butted portion 103′. Furthermore, “WD′” shows thejoining direction in this friction agitation joining method.

[0009] In cases where the joining members 101 and 102 are twisted orcurved in the thickness direction, i.e., not formed into a flat shape,joining of such joining members 101 and 102 causes a defect of shape. Asa result, high quality joined butted members cannot be obtained.Furthermore, if these joining members 101 and 102 are butted againsteach other in the state that they have torsion, clearance (not shown)resulting from the torsion of the joining members 101 and 102 will begenerated at the butted portion 103. Accordingly, if the butted portion103 is joined in this state, a joining defect such as a non-joinedportion will occur in the joined portion 103′ by the clearance.Furthermore, in cases where the joining members are long or thinmembers, even if these members are joined by friction agitation joining,thermal distortion due to the joining tends to be produced.

[0010] In order to solve this problem, Japanese Unexamined Laid-openPatent Publication No. H10-296462 proposes the following method. In thismethod, a butted portion will be joined/welded while pressing thejoining-direction forward side of both the joining members 101 and 102with respect to a probe inserted position from the upper surface sidethereof by a cylindrical forward pressing roller 110 having a certainlength and bridging over both the joining members 101 and 102, and alsopressing the joining-direction backward side of both the joining members101 and 102 with respect to a probe inserted position from the uppersurface side thereof by a cylindrical backward pressing roller 110having a certain length and bridging over both the joining members 101and 102.

[0011] However, since the stepped portion 104 is formed on the surfaceof the butted portion 103 of the joining members 101 and 102, accordingto the aforementioned proposed method, even if the forward and backwardpressing rollers 110 and 120 are intended to press both the joiningmembers 101 and 102, it was able to press down the thicker joiningmember 102 with the forward and backward pressing rollers 110 and 120,but was not able to press down the thinner joining member 101. As aresult, neither torsion nor curvature could be corrected. Therefore, thejoining members 101 and 102 are joined in a state that they have torsionor curvature, and therefore configuration defects, joining defects suchas a non-joined state and thermal distortion occur. Accordingly, highquality joined butted members cannot be obtained.

[0012] Now, generally, in a friction agitation joining method, it isdesirable to execute the joining method in a state in which the probe142 of the joining tool 140 is deeply inserted into the butted portion103 so as to join the butted portion 103 in the entire thicknessdirection thereof.

[0013] However, if the friction agitation joining is performed in astate in which the probe 142 is inserted as mentioned above, the tip ofthe probe 142 may project from the lower surface of the butted portion103 of the joining members 101 and 102 during the joining process, whichin turn may cause a damage to the backing member such as a backingroller 133. In order to prevent such a fault, as shown in FIG. 30,generally the probe 142 is inserted so as to keep the distance betweenthe tip of the probe 142 and the lower surface of the butted portion103. However, this insufficient insertion of the probe 142 causesinsufficient joining of the butted portion 103 with respect to thethickness direction. As a result, as shown in FIG. 31, the rootremaining portion R tends to remain in the lower surface of the joinedbutted portion 103′ where both the joining members 101 and 102 arejoined. This root remaining portion R causes reduced bonding strength ofthe butted joining members.

[0014] As shown in FIGS. 30 and 31, especially in cases where both thejoining members 101 and 102 are butted against each other with a leveldifference formed on the surface side in the thickness direction, theroot remaining portion R tends to remain. That is, in cases where boththe joining members 101 and 102 are butted against each other asmentioned above, it is difficult to stably dispose the end surface 141 aof the rotor 141 of the joining tool 140 on both the joining members 101and 102, and therefore as shown in FIG. 30, the rotor 141 tends toincline to the first joining member side 101 or the second joiningmember side 102 unexpectedly. Thus, at the time of inclination of therotor 141, since the insertion depth of the probe 142 in the buttedportion 103 changes, it is necessary to reduce the insertion depth ofthe probe 142 for safety, which in turn tends to generate the rootremaining portion R.

[0015] Furthermore, as shown in FIG. 30, in this case, since the rotor141 of the joining tool 140 is usually disposed in a inclined statetoward the first joining member side 101, it is difficult to strictlyset the insertion depth of the probe 142 into the butted portion 103.Furthermore, since the insertion depth of the probe 142 increasesbecause the shoulder portion 102 a of the second joining member 102deforms plastically during the joining, it is necessary to decrease theinsertion depth of the probe 142. For this reason, the root remainingportion R tends to remain.

[0016] Furthermore, since the thickness of manufactured joining member101 and 102 is uneven, it is difficult to keep the constant insertiondepth of the probe 142. From this point too, the root remaining portionR tends to remain.

[0017] The present invention was made in view of the aforementionedtechnical background.

[0018] It is a first object of the present invention to provide afriction agitation joining method, a method for manufacturing joinedbutted members and a friction agitation joining apparatus capable ofpreventing a generation of configuration defects such as twist orcurvature and a generation of poor junction such as joint defect orthermal distortion, to thereby provide high quality joined buttedmembers.

[0019] It is a second object of the present invention to provide afriction agitation joining method, a method for manufacturing joinedbutted members and a friction agitation joining apparatus capable ofpreventing a generation of a root remaining portion to thereby providehigh quality joined butted members.

[0020] Other objects and advantages of the present invention will beapparent from the following preferred embodiments.

DISCLOSURE OF INVENTION

[0021] In order to attain the aforementioned first object of the presentinvention, according to the first aspect of the present invention, in afriction agitation joining method for joining a first joining member anda second joining member butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingthe first and second joining members with respect to a rotating probe ofa joining tool inserted into a butted portion of the first and secondjoining members from the upper surface sides so that the probe advancesalong the butted portion, joining of the butted portion is performedwhile pressing joining-direction forward sides of the first joiningmember and the second joining member with respect to a probe insertedposition from the upper surface sides by a first forward pressing rollerand a second forward pressing roller, respectively.

[0022] According to the first aspect of the present invention, bypressing joining-direction forward sides of the first joining member andthe second joining member with respect to a probe inserted position fromthe upper surface sides by a first forward pressing roller and a secondforward pressing roller, respectively, it is possible to prevent a faultsuch as an unexpected movement of each joining member during the joiningand also to correct the configuration defect of each joining member suchas torsion or curvature. Furthermore, performing the joining process inthis state can prevent the generation of poor junction such as jointdefect or thermal distortion, resulting in high quality butted joiningmembers.

[0023] In order to attain the aforementioned first object of the presentinvention, according to the second aspect of the present invention, in afriction agitation joining method for joining a first joining member anda second joining member butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingthe first and second joining members with respect to a rotating probe ofa joining tool inserted into a butted portion of the first and secondjoining members from the upper surface sides so that the probe advancesalong the butted portion, joining of the butted portion is performedwhile pressing joining-direction backward sides of the first joiningmember and the second joining member with respect to a probe insertedposition from the upper surface sides by a first backward pressingroller and a second backward pressing roller, respectively.

[0024] According to the second aspect of the present invention, bypressing joining-direction backward sides of the first joining memberand the second joining member with respect to a probe inserted positionfrom the upper surface sides by a first backward pressing roller and asecond backward pressing roller, respectively, it is possible to preventa fault such as an unexpected movement of each joining member during thejoining and also to correct the configuration defect of each joiningmember such as torsion or curvature. Furthermore, performing the joiningprocess in this state can prevent the generation of poor junction suchas joint defect or thermal distortion, resulting in high quality joinedbutted members.

[0025] In order to attain the aforementioned first object of the presentinvention, according to the third aspect of the present invention, infriction agitation joining method for joining a first joining member anda second joining member butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingthe first and second joining members with respect to a rotating probe ofa joining tool inserted into a butted portion of the first and secondjoining members from the upper surface sides so that the probe advancesalong the butted portion, joining of the butted portion is performedwhile pressing joining-direction forward sides of the first joiningmember and the second joining member with respect to a probe insertedposition from the upper surface sides by a first forward pressing rollerand a second forward pressing roller, respectively, and pressingjoining-direction backward sides of the first joining member and thesecond joining member with respect to a probe inserted position from theupper surface sides by a first backward pressing roller and a secondbackward pressing roller, respectively.

[0026] According to the third aspect of the present invention,joining-direction forward sides of the first joining member and thesecond joining member with respect to a probe inserted position ispressed from the upper surface sides by a first forward pressing rollerand a second forward pressing roller, respectively. Furthermore,joining-direction backward sides of the first joining member and thesecond joining member with respect to a probe inserted position ispressed from the upper surface sides by a first backward pressing rollerand a second backward pressing roller, respectively. Accordingly, it ispossible to prevent a fault such as an unexpected movement of eachjoining member during the joining and also to correct the configurationdefect of each joining member such as torsion or curvature. Furthermore,performing the joining process in this state can prevent the generationof poor junction such as joint defect or thermal distortion, resultingin high quality joined butted members.

[0027] In the first or third aspect of the present invention, a metalmember, for example, may be used as a joining member. Furthermore, atthe time of joining operation, both the joining members are usuallysupported by the support member from the lower surface side thereof. Asthis support member (means), various means including the support rollerwhich will be mentioned later can be used.

[0028] In the aforementioned first or third aspect of the presentinvention, it is preferable that the joining of the butted portion isperformed while pressing at least a portion near the butted portion atthe joining-direction forward side of the first joining member withrespect to a probe inserted position and at least a portion near thebutted portion at the joining-direction forward side of the secondjoining member with respect to a probe inserted position from the uppersurface sides by the first forward pressing roller and the secondforward pressing roller, respectively.

[0029] In this case, each joining member can be pressed assuredly. As aresult, the generation of poor junction such as joint defect or thermaldistortion can be prevented more assuredly, resulting in high qualityjoined butted members.

[0030] In any one of the first to third aspects of the presentinvention, it is preferable that the joining of the butted portion isperformed while pressing a joined butted portion of the first and secondjoining members from the upper surface sides by a third backwardpressing roller with a tapered periphery.

[0031] In this case, by pressing the joined butted portion by the thirdbackward pressing roller, the joined butted portion is pressed by thepressing force from the third backward pressing roller and therebyplastically deformed, so that the surface becomes into an inclinedsurface. Furthermore, due to this plastic deformation, the materials ofthe shoulder portion of the joining members will be filled in the cornerof the stepped portion. Furthermore, minute unevenness, such as a burrwhich may sometimes be generated on the surface of the joined buttedportion, is pressed and removed by receiving the press force from thethird backward pressing roller. Accordingly, the surface of the joinedbutted portion is formed into an inclined surface and smoothed with theinclined state. When the surface of the joined butted portion is formedinto such an inclined surface, the stress concentration produced in thestepped portion of the obtained butted joining members is relieved.Furthermore, when the joined butted portion is pressed as mentionedabove, the tension residual stress produced on the surface of the joinedbutted portion is converted into a compression residual stress, whichenhances the durability of the butted joining members. Furthermore,since the surface of the joined butted portion is smoothed, thegenerating of the film defects due to the aforementioned minuteunevenness which may sometimes be generated at the time of painting canbe prevented. As a result, it becomes possible to form a film on thesurface of the joined butted portion appropriately.

[0032] It is preferable that the periphery of the third backwardpressing roller is cooled. In this case, the upper surface of the joinedbutted portion of the joining members is forcibly cooled by beingcontacted by the cooled periphery of the roller. Thereby, the joinedbutted portion is quenched. Accordingly, the joining strength improves.Furthermore, the superfluous heat produced in the joined butted portionis removed, resulting in, a good joining state.

[0033] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed while cooling a lower surface of a joined buttedportion of the first and second joining members by keeping a cooledperiphery of a cooling roller in contact with the lower surface.

[0034] In this case, the lower surface of the joined butted portion ofthe joining members is forcibly cooled by being contacted by the cooledperiphery of the roller. Thereby, the joined butted portion is quenched.Accordingly, the joining strength improves. Furthermore, the superfluousheat produced in the joined butted portion is removed, resulting in agood joining state.

[0035] In the first or third aspect of the present invention, it ispreferable that the first forward pressing roller and the second forwardpressing roller are separate members, and that the joining of the buttedportion is performed in a state in which an axis of at least one ofrollers including the first forward pressing roller and the secondforward pressing roller is inclined with respect to a butting directionof the joining members within a plane perpendicular to a joiningdirection.

[0036] In this case, since the first forward pressing roller and thesecond forward pressing roller are separate members, even if the thickdimension of at least one of the joining members fluctuates in adirection parallel to the joining direction, the joining members can bepressed firmly. Furthermore, by inclining an axis of at least one ofrollers including the first forward pressing roller and the secondforward pressing roller with respect to the butting direction of thejoining members within a plane perpendicular to the joining direction,the pressing force from the roller received by the joining member can bechanged in the butting direction. Then, by joining the butted portion inthis state, the generation of poor junction such as joint defect orthermal distortion can be prevented more assuredly.

[0037] In the first or third aspect of the present invention, it ispreferable that the first forward pressing roller and the second forwardpressing roller are separate members, and that the joining of the buttedportion is performed while changing at least one of an inclination angleof an axis of the first forward pressing roller with respect to abutting direction of the first joining member within a planeperpendicular to a joining direction and an inclination angle of an axisof the second forward pressing roller with respect to the buttingdirection of the second joining member within a plane perpendicular to ajoining direction based on a measured value of a characteristicconcerning a joint state of a joined butted portion of the first andsecond joining members.

[0038] In this case, a poor junction prevention work can be performedefficiently. As a characteristic concerning the joint state of thejoined butted portion, the surface temperature and its surface residualstress of the joined butted portion can be exemplified.

[0039] In the first or third aspect of the present invention, it ispreferable that the first forward pressing roller and the second forwardpressing roller are separate members, and that the joining of the buttedportion is performed in a state in which an axis of at least one ofrollers including the first forward pressing roller and the secondforward pressing roller is inclined with respect to a butting directionof the joining members within a plane parallel to upper surfaces of thejoining members so that force in a butting direction is given to thejoining members.

[0040] In this case, since the first forward pressing roller and thesecond forward pressing roller are separate members, even if the thickdimension of at least one of the joining members fluctuates in adirection parallel to the joining direction, the joining members can bepressed firmly. Furthermore, by inclining the axis of at least one ofrollers including the first forward pressing roller and the secondforward pressing roller with respect to a butting direction of thejoining members within a plane parallel to upper surfaces of the joiningmembers so that force in a butting direction is given to the joiningmembers, both the joining members come to stick strongly at the buttedportion. Thus, by joining the butted portion in this state of thisadhesion, the joining members can be joined firmly at the buttedportion.

[0041] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed in a state in which the joining-direction forwardsides of the first joining member and the second joining member withrespect to a probe inserted position is supported from lower surfacesides thereof by a first forward supporting roller and a second forwardsupporting roller separated from the first forward supporting roller,respectively, and an axis of at least one of rollers including the firstforward supporting roller and the second forward supporting roller isinclined with respect to a butting direction of the joining memberswithin a plane parallel to lower surfaces of the joining members so thatforce in a butting direction is given to the joining members.

[0042] In this case, both the joining members come to stick strongly atthe butted portion. Thus, by joining the butted portion in this state ofthis adhesion, the joining members can be joined firmly at the buttedportion.

[0043] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed in a state in which the joining-direction backwardsides of the first joining member and the second joining member withrespect to a probe inserted position is supported from lower surfacesides thereof by a first backward supporting roller and a secondbackward supporting roller separated from the first backward supportingroller, respectively.

[0044] In this case, by using a backward supporting roller divided intothe first backward supporting roller and the second backward supportingroller, the design freedom of the backward supporting roller increases.Accordingly, for example, by changing the mutual arrangement of thefirst backward supporting roller or the second backward supportingroller or changing the circumferential speed thereof, a meanderingmovement of the joining members which may be generated at the time ofthe movement of the joining members can be prevented, and thestraightening effect to the configuration defect of each joining membercan be expected.

[0045] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed in a state in which tension in a direction parallelto a joining direction is given to at least one of the first joiningmember and the second joining member.

[0046] In this case, configuration defects, such as curvature, twist anddeflection, can be corrected, and surface vibration of each joiningmember can be suppressed. By joining the butted portion in this state,the quality of the butted joining members to be obtained can beimproved.

[0047] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed while heating a lower surface of a probe insertedposition of the butted portion or a lower surface of a joining-directionforward side of the probe inserted position.

[0048] In this case, heat conducts in the thickness direction from thelower surface of both the joining members, and the portion near thelower surface in the thickness direction becomes high in temperature.Accordingly, the materials between the tip of the probe and the lowersurface of the joining members can be softened quickly at the time ofjoining, preventing the generation of the root remaining portion, whichresults in increased joining strength.

[0049] As a heating apparatus for heating the lower surface of both thejoining members, a heating roller having a heated periphery to becontacted to the lower surface of the probe inserted position or thelower surface of the joining-direction forward side of the probeinserted position at the butted portion of the joining members, a laserirradiation heating apparatus, or a high frequency induction heatingapparatus can be used suitably. Furthermore, in cases where at least oneof the joining members is made of an aluminum or its alloy, it isespecially preferable that the lower surface is heated such that thetemperature of the lower surface falls within the range of from 400 to500° C.

[0050] In any one of the aforementioned first to third aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed while relatively moving the first and secondjoining members with respect to a rotating sub-probe of a sub-joiningtool inserted into the butted portion of the first and second joiningmembers or a joined butted portion from a lower surface side thereof sothat the probe and the sub-probe advance along the butted portion.

[0051] In this case, the butted portion is joined while the rootremaining portion is joined by the sub-probe of the sub-joining tool.Accordingly, the generation of root remaining portion can be prevented(suppressed), and the joining strength can be improved.

[0052] It is preferable that the insertion depth of the sub-probe of thesub-joining tool into the butted portion or the joined butted portionfrom the lower surface thereof falls within the range of from 0.1 to 0.5mm. The reasons are as follows. If the insertion depth is less than 0.1mm, there is a possibility that the insertion depth may be insufficientand therefore the root remaining portion may remain. On the other hand,if the insertion depth exceeds 0.5 mm, the force required for movingboth the joining members becomes large, and therefore it becomesdifficult to move the joining members. Accordingly, it is preferablethat the insertion depth falls within the range of from 0.1 to 0.5 mm.Furthermore, it is especially preferable that the insertion depth is setso as to fall within the aforementioned range in cases where the twojoining members are different in wall thickness and the wall thicknessof the thinner joining member is 3 mm or less. Furthermore, it is alsoespecially preferable to set the insertion depth to the aforementionedrange in cases where the wall thickness of two joining members is thesame and 3 mm or less.

[0053] In order to attain the aforementioned second object, according tothe fourth aspect of the present invention, in a friction agitationjoining method for joining a first joining member and a second joiningmember butted against each other by relatively moving the first andsecond joining members with respect to a rotating probe of a joiningtool inserted into a butted portion of the first and second joiningmembers from upper surface sides thereof so that the probe advancesalong the butted portion, the joining of the butted portion is performedwhile heating a lower surface of a probe inserted position of the buttedportion or a lower surface of a joining-direction forward side of theprobe inserted position.

[0054] In the friction agitation joining method according to the fourthaspect of the present invention, heat conducts in the thicknessdirection from the lower surface of both the joining members, and theportion near the lower surface in the thickness direction becomes highin temperature. Accordingly, the materials between the tip of the probeand the lower surface of the joining members can be softened quickly atthe time of joining, preventing the generation of the root remainingportion, which results in increased joining strength.

[0055] As a heating apparatus for heating the lower surface of both thejoining members, the aforementioned heating roller, a laser irradiationheating apparatus, or a high frequency induction heating apparatus canbe used suitably. Furthermore, in cases where at least one of thejoining members is made of an aluminum or its alloy, it is especiallypreferable that the lower surface is heated such that the temperature ofthe lower surface falls within the range of from 400 to 500° C.Furthermore, in this fourth aspect of the present invention, the wallthickness of the two joining members may be the same or different witheach other. Furthermore, the two joining members may be arranged suchthat the level difference is formed at the upper surface side of boththe joining members. Alternatively, they may be arranged such that thelevel difference is not formed at the upper surface side thererof.

[0056] In the aforementioned fourth aspect of the present invention, itis preferable that the heating is performed by heat conduction from aheated periphery of a backing roller disposed opposite to the probe at alower surface side of the joining members.

[0057] In this case, the heated periphery of the backing roller iscontacted to the lower surface of the probe insertion position of thebutted portion of the joining members at the time of joining. Thereby,the heat of the periphery of the backing roller conducts at the lowersurfaces of the joining members, and therefore the lower surfaces areheated. Thus, the butted portion is joined while being heated.Accordingly, the joining operation can be performed efficiently.Furthermore, since the lower surface of the probe inserted position atthe butted portion of the joining members is heated, the heat loss issmall, and therefore the heating can be performed efficiently.

[0058] In order to attain the aforementioned second object, according tothe fifth aspect of the present invention, in a friction agitationjoining method for joining a first joining member and a second joiningmember butted against each other with upper and lower surfaces beingflush with each other by relatively moving the first and second joiningmembers with respect to a rotating probe of a joining tool inserted intoa butted portion of the first and second joining members from uppersurface sides thereof so that the probe advances along the buttedportion, the joining of the butted portion is performed while relativelymoving the first and second joining members with respect to a rotatingsub-probe of a sub-joining tool inserted into the butted portion of thefirst and second joining members or a joined butted portion from a lowersurface side thereof so that the probe and the sub-probe advance alongthe butted portion.

[0059] In this case, the butted portion is joined while the rootremaining portion is joined by the sub-probe of the sub-joining tool.Accordingly, the generating of root remaining portion can be prevented(suppressed), and the joining strength can be improved.

[0060] In the aforementioned fifth aspect of the present invention, itis preferable that an insertion depth of the sub-probe is regulatedwithin the range of from 0.1 to 0.5 mm. The reasons have been mentionedabove. Furthermore, in cases where the thickness of the joining memberis 3 mm or less, it is preferable that the insertion depth of thesub-probe is set so as to fall within the aforementioned range.

[0061] In order to attain the aforementioned first object, according tothe sixth aspect of the present invention, in method for manufacturingjoined butted members by performing a friction agitation joining methodfor joining a first joining member and a second joining member buttedagainst each other with a level difference formed at upper surface sidesthereof by relatively moving the first and second joining members withrespect to a rotating probe of a joining tool inserted into a buttedportion of the first and second joining members from the upper surfacesides so that the probe advances along the butted portion, joining ofthe butted portion is performed while pressing joining-direction forwardsides of the first joining member and the second joining member withrespect to a probe inserted position from the upper surface sides by afirst forward pressing roller and a second forward pressing roller,respectively.

[0062] According to the method of the sixth aspect of the presentinvention, the same function as in the first aspect of the presentinvention can be obtained.

[0063] In order to attain the aforementioned first object, according tothe seventh aspect of the present invention, in a method formanufacturing joined butted member by performing a friction agitationjoining method for joining a first joining member and a second joiningmember butted against each other with a level difference formed at uppersurface sides thereof by relatively moving the first and second joiningmembers with respect to a rotating probe of a joining tool inserted intoa butted portion of the first and second joining members from the uppersurface sides so that the probe advances along the butted portion,joining of the butted portion is performed while pressingjoining-direction backward sides of the first joining member and thesecond joining member with respect to a probe inserted position from theupper surface sides by a first backward pressing roller and a secondbackward pressing roller, respectively.

[0064] According to the method of the seventh aspect of the presentinvention, the same function as in the second aspect of the presentinvention can be obtained.

[0065] In order to attain the aforementioned first object, according tothe eighth aspect of the present invention, in a method formanufacturing joined butted members by performing a friction agitationjoining method for joining a first joining member and a second joiningmember butted against each other with a level difference formed at uppersurface sides thereof by relatively moving the first and second joiningmembers with respect to a rotating probe of a joining tool inserted intoa butted portion of the first and second joining members from the uppersurface sides so that the probe advances along the butted portion,joining of the butted portion is performed while pressingjoining-direction forward sides of the first joining member and thesecond joining member with respect to a probe inserted position from theupper surface sides by a first forward pressing roller and a secondforward pressing roller, respectively, and pressing joining-directionbackward sides of the first joining member and the second joining memberwith respect to a probe inserted position from the upper surface sidesby a first backward pressing roller and a second backward pressingroller, respectively.

[0066] According to the method of the eighth aspect of the presentinvention, the same function as in the third aspect of the presentinvention can be obtained.

[0067] In any one of the aforementioned sixth to eighth aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed while heating a lower surface of a probe insertedposition of the butted portion or a lower surface of a joining-directionforward side of the probe inserted position.

[0068] In this case, the generating of the root remaining portion can beprevented, and the joining strength can be improved.

[0069] In any one of the aforementioned sixth to eighth aspects of thepresent invention, it is preferable that the joining of the buttedportion is performed while relatively moving the first and secondjoining members with respect to a rotating sub-probe of a sub-joiningtool inserted into the butted portion of the first and second joiningmembers or a joined butted portion from a lower surface side thereof sothat the probe and the sub-probe advance along the butted portion.

[0070] In this case, the generating of the root remaining portion can beprevented, and the joining strength can be improved.

[0071] In order to attain the aforementioned second object, according tothe ninth aspect of the present invention, in a method for manufacturingjoined butted members by performing a friction agitation joining methodfor joining a first joining member and a second joining member buttedagainst each other by relatively moving the first and second joiningmembers with respect to a rotating probe of a joining tool inserted intoa butted portion of the first and second joining members from uppersurface sides thereof so that the probe advances along the buttedportion, the joining of the butted portion is performed while heating alower surface of a probe inserted position of the butted portion or alower surface of a joining-direction forward side of the probe insertedposition.

[0072] In this case, the generating of the root remaining portion can beprevented, and the joining strength can be improved.

[0073] In order to attain the aforementioned second object, according tothe tenth aspect of the present invention, in a method for manufacturingjoined butted members by performing a friction agitation joining methodfor joining a first joining member and a second joining member buttedagainst each other with upper and lower surfaces being flush with eachother by relatively moving the first and second joining members withrespect to a rotating probe of a joining tool inserted into a buttedportion of the first and second joining members from upper surface sidesthereof so that the probe advances along the butted portion, the joiningof the butted portion is performed while relatively moving the first andsecond joining members with respect to a rotating sub-probe of asub-joining tool inserted into the butted portion of the first andsecond joining members or a joined butted portion from a lower surfaceside thereof so that the probe and the sub-probe advance along thebutted portion.

[0074] In this case, the generating of the root remaining portion can beprevented, and the joining strength can be improved.

[0075] In order to attain the aforementioned first object, according tothe eleventh aspect of the present invention, a friction agitationjoining apparatus for joining a first joining member and a secondjoining member butted against each other with a level difference formedat upper surface sides thereof by relatively moving the first and secondjoining members with respect to a rotating probe of a joining toolinserted into a butted portion of the first and second joining membersfrom the upper surface sides so that the probe advances along the buttedportion, comprises: a first forward pressing roller for pressingjoining-direction forward side of the first joining member with respectto a probe inserted position from upper surface side thereof; and asecond forward pressing roller for pressing joining-direction forwardside of the second joining member with respect to the probe insertedposition from upper surface side thereof.

[0076] With the friction agitation joining apparatus according to theeleventh aspect of the present invention, the friction agitation joiningmethod according to the first aspect of the present invention or themethod for manufacturing joined butted members according to the sixthaspect of the present invention can be performed efficiently.

[0077] In order to attain the aforementioned first object, according tothe twelfth aspect of the present invention, a friction agitationjoining apparatus for joining a first joining member and a secondjoining member butted against each other with a level difference formedat upper surface sides thereof by relatively moving the first and secondjoining members with respect to a rotating probe of a joining toolinserted into a butted portion of the first and second joining membersfrom the upper surface sides so that the probe advances along the buttedportion, comprises: a first backward pressing roller for pressingjoining-direction backward side of the first joining member with respectto a probe inserted position from upper surface side thereof; and asecond backward pressing roller for pressing joining-direction backwardside of the second joining member with respect to the probe insertedposition from upper surface side thereof.

[0078] With the friction agitation joining apparatus according to thetwelfth aspect of the present invention, the friction agitation joiningmethod according to the second aspect of the present invention or themethod for manufacturing joined butted members according to the seventhaspect of the present invention can be performed efficiently.

[0079] In order to attain the aforementioned first object, according tothe thirteenth aspect of the present invention, a friction agitationjoining apparatus for joining a first joining member and a secondjoining member butted against each other with a level difference formedat upper surface sides thereof by relatively moving the first and secondjoining members with respect to a rotating probe of a joining toolinserted into a butted portion of the first and second joining membersfrom the upper surface sides so that the probe advances along the buttedportion, comprises: a first forward pressing roller for pressingjoining-direction forward side of the first joining member with respectto a probe inserted position from upper surface side thereof; and asecond forward pressing roller for pressing joining-direction forwardside of the second joining member with respect to the probe insertedposition from upper surface side thereof; a first backward pressingroller for pressing joining-direction backward side of the first joiningmember with respect to a probe inserted position from upper surface sidethereof; and a second backward pressing roller for pressingjoining-direction backward side of the second joining member withrespect to the probe inserted position from upper surface side thereof.

[0080] With the friction agitation joining apparatus according to thethirteenth aspect of the present invention, the friction agitationjoining method according to the third aspect of the present invention orthe method for manufacturing joined butted members according to theeighth aspect of the present invention can be performed efficiently.

[0081] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a thirdbackward pressing roller having a tapered periphery for pressing ajoined butted portion of the joining members from surface sides thereof.

[0082] It is preferable that the periphery of the third backwardpressing roller is cooled.

[0083] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a coolingroller for cooling a lower surface of a joined butted portion of thefirst and second joining members by keeping a cooled periphery of thecooling roller in contact with the lower surface.

[0084] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable that the first forwardpressing roller and the second forward pressing roller are separatemembers, and further comprising an inclination angle changing apparatusfor changing an inclination angle of an axis of at least one of rollersincluding the first forward pressing roller and the second forwardpressing roller with respect to a butting direction of the joiningmembers within a plane perpendicular to a joining direction.

[0085] Furthermore, it is preferable to further comprise a measuringdevice for measuring a characteristic concerning a joint state of ajoined butted portion of the joining members, and a controller forcontrols an operation of the inclination angle changing apparatus basedon a measured value obtained by the measuring device.

[0086] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable that the first forwardpressing roller and the second forward pressing roller are separatemembers, and further comprising an inclination angle changing apparatusfor changing an inclination angle of an axis of at least one of rollersincluding the first forward pressing roller and the second forwardpressing roller with respect to a butting direction of the joiningmembers within a plane parallel to upper surfaces of the joiningmembers.

[0087] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise ameasuring device for measuring a characteristic concerning a joint stateof a joined butted portion of the joining members, and a controller forcontrols an operation of the inclination angle changing apparatus basedon a measured value obtained by the measuring device.

[0088] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a firstforward supporting roller for supporting the joining-direction forwardside of the first joining member with respect to a probe insertedposition from a lower surface side thereof, a second forward supportingroller for supporting the joining-direction forward side of the secondjoining member with respect to a probe inserted position from a lowersurface side thereof, the second forward supporting roller beingseparated from the first forward supporting roller, and an inclinationangle changing apparatus for changing an inclination angle of an axis ofat least one of rollers including the first forward supporting rollerand the second forward supporting roller with respect to a buttingdirection of the joining members within a plane parallel to lowersurfaces of the joining members.

[0089] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a firstbackward supporting roller for supporting the joining-direction backwardside of the first joining member with respect to a probe insertedposition from a lower surface side thereof, and a second backwardsupporting roller for supporting the joining-direction forward side ofthe second joining member with respect to a probe inserted position froma lower surface side thereof, the second backward supporting rollerbeing separated from the first backward supporting roller.

[0090] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a tensiondevice for giving tension in a direction parallel to a joining directionto at least one of the first joining member and the second joiningmember.

[0091] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise a heatingdevice for heating a lower surface of a probe inserted position of thebutted portion or a lower surface of a joining-direction forward side ofthe probe inserted position.

[0092] In any one of the aforementioned eleventh to thirteenth aspectsof the present invention, it is preferable to further comprise asub-joining tool having a rotatable sub-probe, wherein the rotatingsub-probe is inserted into the butted portion or a joined butted portionwhen the butted portion is joined or is being joined to join a rootremaining portion produced at the joined butted portion of the joiningmembers.

[0093] In order to attain the aforementioned second object, according tothe fourteenth aspect of the present invention, a friction agitationjoining apparatus for joining a first joining member and a secondjoining member butted against each other by relatively moving the firstand second joining members with respect to a rotating probe of a joiningtool inserted into a butted portion of the first and second joiningmembers from the upper surface sides so that the probe advances alongthe butted portion, comprises a heating device for heating a lowersurface of a probe inserted position of the butted portion or a lowersurface of a joining-direction forward side of the probe insertedposition.

[0094] With the friction agitation joining apparatus according to thefourteenth aspect of the present invention, the friction agitationjoining method according to the fourth aspect of the present inventionor the method for manufacturing joined butted members according to theninth aspect of the present invention can be performed efficiently.

[0095] In order to attain the aforementioned second object, according tothe fifteenth aspect of the present invention, a friction agitationjoining apparatus for joining a first joining member and a secondjoining member butted against each other with upper and lower surfacesbeing flush with each other by relatively moving the first and secondjoining members with respect to a rotating probe of a joining toolinserted into a butted portion of the first and second joining membersfrom upper surface sides thereof so that the probe advances along thebutted portion, comprises a sub-joining tool having a rotatablesub-probe, wherein the rotating sub-probe is inserted into the buttedportion or a joined butted portion when the butted portion is joined oris being joined to join a root remaining portion produced at the joinedbutted portion of the joining members.

[0096] With the friction agitation joining apparatus according to thefifteenth aspect of the present invention, the friction agitationjoining method according to the fifth aspect of the present invention orthe method for manufacturing joined butted members according to thetenth aspect of the present invention can be performed efficiently.

[0097] In the present invention, the language “upper surface side” meansa side from which a (main) rotating probe is inserted, and “lowersurface side” means a side opposite to the “upper surface side”, i.e., aside opposite to the side from which a (main) rotating probe isinserted.

BRIEF DESCRIPTION OF DRAWINGS

[0098]FIG. 1 is a side view showing the state in the middle of joiningthe butted portion of both the joining members by the friction agitationjoining method according to the first embodiment of the presentinvention.

[0099]FIG. 2 is an enlarged perspective view showing the Z part shown inFIG. 1.

[0100]FIG. 3 is a side view of FIG. 2.

[0101]FIG. 4 is a cross-sectional view taken along the line A-A in FIG.2.

[0102]FIG. 5 is a cross-sectional view taken along the line B-B FIG. 2;

[0103]FIG. 6 is an enlarged cross-sectional view taken along the lineC-C in FIG. 2.

[0104]FIG. 7 is an enlarged cross-sectional view taken along the lineD-D in FIG. 2.

[0105]FIG. 8 is a front view showing forward pressing rollers andbackward pressing rollers used in the embodiments and the comparativeembodiments.

[0106]FIG. 9 is a perspective view corresponding to FIG. 2 showing thestate in the middle of joining the butted portion of both the joiningmembers by the friction agitation joining method according to the secondembodiment of the present invention.

[0107]FIG. 10 is a structural view showing the forward pressing rollersand the forward supporting rollers as seen from the front side thereoffor explaining one operation of these rollers.

[0108]FIG. 11 is a structural view showing the forward pressing rollersas seen from the upper surface side of both the joining members forexplaining one operation of these rollers.

[0109]FIG. 12 is a structural view showing the forward supportingrollers as seen from the upper surface side of the joining members forexplaining one operation of these rollers.

[0110]FIG. 13 is a plane view showing the joining-direction forward sideof both the joining members with respect to the probe inserted position.

[0111]FIG. 14 is a structural view showing the forward pressing rollersand the forward supporting rollers as seen from the front side thereoffor explaining the other operation of these rollers.

[0112]FIG. 15 is a cross-sectional view showing both the joining membersfor explaining the other operation of the forward pressing rollers.

[0113]FIG. 16 is a cross-sectional view taken along the line E-E in FIG.9.

[0114]FIG. 17 is a perspective view corresponding to FIG. 2 showing thestate in the middle of joining the butted portion of both the joiningmembers by the friction agitation joining method according to the thirdembodiment of the present invention.

[0115]FIG. 18 is a cross-sectional view taken along the line F-F in FIG.17.

[0116]FIG. 19 is a cross-sectional view taken along the line G-G in FIG.17.

[0117]FIG. 20 is a cross-sectional view taken along the line H-H in FIG.17.

[0118]FIG. 21 is across-sectional view taken along the line I-I in FIG.17.

[0119]FIG. 22 is a cross-sectional view corresponding to FIG. 18 showingthe friction agitation joining method according to the fourth embodimentof the present invention.

[0120]FIG. 23 is a cross-sectional view taken along the line J-J in FIG.22.

[0121]FIG. 24 is a cross-sectional view corresponding to FIG. 18 showingthe friction agitation joining method according, to the fifth embodimentof the present invention.

[0122]FIG. 25 is a cross-sectional view taken along the line K-K in FIG.24.

[0123]FIG. 26 is a perspective view corresponding to FIG. 17 showing thefriction agitation joining method according to the sixth embodiment ofthe present invention.

[0124]FIG. 27 is a cross-sectional view taken along the line L-L in FIG.26.

[0125]FIG. 28 is a cross-sectional view taken along the line M-M in FIG.26.

[0126]FIG. 29 is a perspective view showing the state in the middle ofjoining the butted portion of both the joining members by a conventionalfriction agitation joining method.

[0127]FIG. 30 is a cross-sectional view of both the joining members atthe probe inserted position.

[0128]FIG. 31 is a cross-sectional view of the joining members in ajoined state.

BEST MODE FOR CARRYING OUT THE INVENTION

[0129] In order to explain the present invention in detail, thepreferred six embodiments according to the present invention will beexplained with reference to the attached drawings.

[0130] First Embodiment

[0131] FIGS. 1 to 7 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining apparatus according to the first embodimentof the present invention. FIG. 1 is a side view showing the state in themiddle of joining the butted portion of both the joining members by thefriction agitation joining method. FIG. 2 is an enlarged perspectiveview showing the Z portion in FIG. 1.

[0132] In FIG. 2, “1” denotes a thin and long plate-shaped first joiningmember, and “2” denotes a thick and long plate-shaped second joiningmember. Each of these joining members 1 and 2 is made of aluminum or itsalloy. In this figure, “80” denotes a friction agitation joiningapparatus according to the first embodiment. The butted joining membersobtained by the friction agitation joining method is used as, forexample, tailored blank materials for automobiles.

[0133] Each joining member 1 and 2 has an upper surface and a lowersurface parallel with each other as shown in FIG. 4, and thecorresponding widthwise side edges are to be butted against each other.This widthwise side edge is formed to be perpendicular to the upper andlower surfaces of the joining member. The width wise side edges of thesetwo joining members 1 and 2 are butted against each other with the lowersurfaces of the joining members being flush with each other (“3” denotesthe butted portion). Accordingly, a stepped portion corresponding to thethickness difference is formed at the upper surface side of the joiningmembers. “4” denotes a stepped portion formed on the upper surfaces ofthe joining members 1 and 2. “4 a” denotes the corner portion of thisstepped portion 4. Furthermore, “N” denotes a butting direction of eachjoining member 1 and 2. This butting direction N is parallel to thewidth direction of the joining member.

[0134] As shown in FIG. 2, in this butted state, both the joiningmembers 1 and 2 are supported by the support members 30 in a horizontalstate. In this first embodiment, a forward supporting roller 31 and abackward supporting roller 32 are used as a supporting member 30.

[0135] Furthermore, as shown in FIG. 1, each joining member 1 and 2 ispulled in the longitudinal direction by forward tension rollers 70 andbackward tension rollers 70 equipped to a tension leveler as a tensiondevice in the state in which each joining member is supported by thesupporting members 30. Thereby, tension in the longitudinal direction isgiven to each joining member 1 and 2.

[0136] In FIG. 2, “40” denotes a joining tool for friction agitationjoining. This joining tool 40 is equipped with a columnar rotor 41having a larger diameter and a pin-shaped probe 42 having a smallerdiameter. The probe 42 is projected from the rotational center of theend face 41 a of the rotor 41 along the rotation axis Q. In FIG. 2, thisprobe 42 of the joining tool 40, which is rotating about the rotationaxis Q, is inserted into the butted portion 3 of the joining members 1and 2 from the upper surface side of the joining members. In thisinserted state, as shown in FIG. 5, the rotation axis Q of the rotor 41and the probe 42 is arranged in the state in which the rotation axis Qis inclined toward the first joining member 1 (namely, the joiningmember at the lower level side). The end face 41 a of the rotor 41 isdisposed in the state in which the end face 41 a is pressed against theshoulder portion 2 a of the second joining member 2 (namely, theshoulder portion of the joining member at the higher level) projectedfrom the butted portion 3. In FIG. 5, “T” denotes a normal line of thesurface at the probe inserted position of the joining members. “θ”denotes the inclination angle of the rotation axis Q toward the firstjoining member 1 with respect to the aforementioned “T.”

[0137] In this joining tool 40, both of the rotor 41 and the probe 42are made of heat-resisting materials that is harder than the joiningmembers 1 and 2 and that can bear frictional heat generated at the timeof joining. On the periphery of the probe 42, agitating protrusions (notshown) for agitating the materials of the joining members 1 and 2softened by frictional heat are formed in a spiral manner or the like.

[0138] In FIG. 5, “D” denotes the diameter of the end face 41 a of therotor 41. At least the peripheral edge of the end face 41 a of thisrotor 41 is formed within a plane perpendicular to the rotation axis Q.In this first embodiment, the end face 41 a of the rotor 41 is a flatsurface. In addition, in the present invention, although it is notillustrated, the end face 41 a of the rotor 41 may be formed into aconfiguration depressing toward the center of the rotation from theperipheral edge thereof.

[0139] In this first embodiment, as shown in FIG. 2, the butted portion3 of both the joining members 1 and 2 are to be joined by moving thejoining members 1 and 2 in one longitudinal direction thereof (themoving direction is shown as “MD”) in a state in which the probe 42 isinserted from the upper surface side into the butted portion 3 asmentioned above and the tension in the longitudinal direction of thejoining members 1 and 2 is given to both the joining members 1 and 2 sothat the probe 42 advances the butted portion 3. Accordingly, in thisfirst embodiment, the joining direction WD coincides with a directionopposite to the moving direction MD of the joining members 1 and 2.Furthermore, the longitudinal direction of each joining member 1 and 2coincides with a direction parallel to the joining direction WD. In FIG.2, “3′” denotes the joined butted portion of the joining members 1 and 2joined by the probe 42. “W” denotes a joined portion formed in thejoined butted portion 3′.

[0140] At the time of joining, as shown in FIG. 3, the rotation axis Qof the joining tool 40 is slightly inclined toward the joining-directionbackward side. Thereby, the joining-direction forward side of the endface 41 a of the rotor 41 is lifted up from the upper surface of thejoining members 1 and 2. This prevents the joining-direction forwardside of the end face 41 a of the rotor 41 from being caught by theminute unevenness which may exist on the upper surface of the joiningmembers 1 and 2, resulting in a smooth advancing movement of the probe42 along the butted portion 3.

[0141] Next, the structure of the friction agitation joining apparatus80 according to the first embodiment will be explained. In FIG. 2, “33”denotes a backing roller. This backing roller 33 has a columnar-shapehaving a predetermined length. This backing roller 33 is disposed at thelower surface side of the joining members 1 and 2 such that the rolleris opposed to the probe 42 of the joining tool 40 and bridges over boththe joining members 1 and 2. By this backing roller 33, joining members1 and 2 are supported at the lower surface of the probe insertedposition of the butted portion 3. This backing roller 33 also plays arole for supporting both the joining members 1 and 2 as a supportingmember 30.

[0142] The support member 30 is equipped with the forward supportingroller 31 and the backward supporting roller 32. The forward supportingroller 31 is a column-shaped member having a predetermined length.Similarly, the backward supporting roller 32 is a column-shaped memberhaving a predetermined length. At the joining-direction forward side ofthe joining members 1 and 2 with respect to the probe inserted position,the forward supporting roller 31 is disposed at the lower surface sideof the joining members 1 and 2 in a state in which the axis of theroller 31 is parallel to the butting direction N and the roller 31bridges over both the joining members 1 and 2. Similarly, at thejoining-direction backward side of the joining members 1 and 2 withrespect to the probe inserted position, the backward supporting roller32 is disposed at the lower surface side of the joining members 1 and 2in a state in which the axis of the roller 32 is parallel to the buttingdirection N and the roller 32 bridges over both the joining members 1and 2. By these forward supporting roller 31 and the backward supportingroller 32, both the joining members 1 and 2 are supported from the lowersurface side thereof at the joining-direction forward side and thejoining-direction backward side of the joining members 1 and 2 withrespect to the probe inserted position.

[0143] The forward supporting roller 31, the backward supporting roller32 and the backing roller 33 are connected to a rotation driving device(not shown). By operating this rotation driving device, these rollers31, 32 and 33 are rotated about the axis thereof at a constantcircumferential speed at a fixed position, respectively. Accordingly,these rollers 31, 32 and 33 also function as driving rollers for movingthe joining members 1 and 2 in a prescribed direction MD. In the presentinvention, the backing roller 33 may be rotated freely. Furthermore, theforward and backward supporting rollers 31 and 32 may be rotated freelyin cases where a driving device for moving the joining members 1 and 2in the predetermined direction MD is provided separately.

[0144] Furthermore, the backward supporting roller 32 also functions asa cooling roller. That is, at the peripheral surface portion of thebackward supporting roller 31, a plurality of coolant circulationpassages 35 arranged in the circumferential direction thereof areprovided. Each passage extends in the longitudinal direction of theroller 32. The coolant (e.g., cooling water) is circulating in thesecoolant circulation passages 35. Thereby, the peripheral portion of thebackward supporting roller 32 is in a cooled state. At the time ofsupporting the joining members 1 and 2, the cooled peripheral portion ofthe backward supporting roller 32 comes into contact with the lowersurface of the joined butted portion 3′, to thereby cool the joinedbutted portion 3′ from the lower surface thereof.

[0145] In FIG. 2, “11” denotes a first forward pressing roller. “12”denotes a second forward pressing roller. The first forward pressingroller 11 is a rotatable columnar-shaped member having a larger diameterand a predetermined length. The second forward pressing roller 12 is arotatable columnar-shaped member having a smaller diameter and apredetermined length. As shown in FIGS. 2 and 4, at the upper surfaceside of the first joining member 1, the first forward pressing roller 11is disposed above the forward supporting roller 31 in a state in whichthe axis P1 of the roller 11 is parallel to the butting-direction N ofthe first joining member 1 at the joining-direction forward side of thefirst joining member 1 with respect to the probe inserted position.Similarly, at the upper surface side of the second joining member 2, thesecond forward pressing roller 12 is disposed above the forwardsupporting roller 31 in a state in which the axis P2 of the roller 12 isparallel to the butting-direction N of the second joining member 2 atthe joining-direction forward side of the second joining member 2 withrespect to the probe inserted position.

[0146] In this first embodiment, the first forward pressing roller 11and the second forward pressing roller 12 are integrally connected in astate in which the axes thereof are arranged on the same straight-lineand the end faces thereof are butted against each other. This integratedroller 10 is referred to as “forward pressing roller” in this firstembodiment.

[0147] In this forward pressing roller 10, the difference between theradius of the first forward pressing roller 11 and that of the secondpressing roller 12 coincides with the level difference formed on theupper surface of the joining members 1 and 2 (namely, theheight-difference between the upper surface of the first joining member1 and that of the second joining member 2).

[0148] By the first forward pressing roller 11, the area at thejoining-direction forward side of the first joining member 1 coveringfrom the widthwise intermediate portion of the first joining member 1 tothe portion near the butted portion 3 is pressed downwardly from theupper surface side. Similarly, by the second forward pressing roller 12,the area at the joining-direction forward side of the first joiningmember 2 covering from the widthwise intermediate portion of the secondjoining member 2 to the portion near the butted portion 3 is presseddownwardly from the upper surface side.

[0149] Since the forward pressing rollers 10 presses these joiningmembers 1 and 2, the lower surfaces of the joining members 1 and 2 arepressed against the periphery of the forward supporting roller 31.Thereby, driving force in the moving direction MD can be given to thejoining members 1 and 2. On the other hand, in accordance with themovement of these joining member 1 and 2, the first and second forwardpressing rollers 11 and 12 integrally rotate about the axis P1 and P2 ata predetermined position.

[0150] In FIG. 2, “21” and “22” denote a first backward pressing rollerand a second backward pressing roller, respectively. The first backwardpressing roller 21 is a rotatable column-shaped member having a largerdiameter and a predetermined length. The second backward pressing roller22 is a rotatable column-shaped member having a smaller diameter and apredetermined length.

[0151] As shown in FIGS. 2 and 7, at the upper surface side of the firstjoining member 1, the first backward pressing roller 21 is disposedabove the backward supporting roller 32 in a state in which the axis ofthe roller 21 is parallel to the butting-direction N of the firstjoining member 1 at the joining-direction backward side of the firstjoining member 1 with respect to the probe inserted position. Similarly,at the upper surface side of the second joining member 2, the secondbackward pressing roller 22 is disposed above the backward supportingroller 32 in a state in which the axis of the roller 22 is parallel tothe butting-direction N of the second joining member 2 at thejoining-direction backward side of the second joining member 2 withrespect to the probe inserted position. In FIG. 2, “23” is a thirdbackward pressing roller. This third backward pressing roller 23 is arotatable truncated cone-shaped member, and therefore the peripheralsurface thereof is a tapered surface. This third backward pressingroller 23 is used for pressing the joined butted portion 3′ of thejoining members 1 and 2 from the upper surface thereof. At the uppersurface side of the joining members 1 and 2, the third backward pressingroller 23 is disposed above the backward supporting roller 32 in a statein which the axis of the roller 23 is parallel to the butting-directionN of the joining members 1 or 2.

[0152] In this first embodiment, the first backward pressing roller 21,the third backward pressing roller 23 and the second backward pressingroller 22 are integrally connected in a state in which the axes arearranged on the same straight line in this order and adjacent end facesare butted against each other. This integrated roller 20 is referred toas a “backward pressing roller” in the first embodiment.

[0153] In this backward pressing roller 20, the difference between theradius of the first backward pressing roller 21 and the second backwardpressing roller 22 coincides with the level difference formed on theupper surfaces of the joining members 1 and 2. Furthermore, theperiphery of the first backward pressing roller 21 and the periphery ofthe second backward pressing roller 22 are continuously connected viathe periphery (namely, tapered surface) of the third backward pressingroller 23.

[0154] By the first backward pressing roller 21, the area at thejoining-direction backward side of the first joining member 1 coveringfrom the widthwise intermediate portion of the first joining member 1 tothe portion near the joined butted portion 3′ is pressed downwardly fromthe upper surface side. Similarly, by the second backward pressingroller 22, the area at the joining-direction backward side of the secondjoining member 2 covering from the widthwise intermediate portion of thesecond joining member 2 to the portion near the joined butted portion 3′is pressed downwardly from the upper surface side.

[0155] Furthermore, at the peripheral surface portion of the thirdbackward pressing roller 23, as shown in FIG. 2, a plurality of coolantcirculation passages 25 arranged in the circumferential directionthereof are provided. Each passage extends in the longitudinal directionof the roller 23 so as to penetrate the first backward pressing roller21 and the second backward pressing roller 22. The coolant (e.g.,cooling water) is circulating in these coolant circulation passages 25.Thereby, the peripheral portion of the third backward pressing roller 23is in a cooled state. At the time of pressing the joined butted portion3′, the cooled peripheral portion of the third backward pressing roller23 comes into contact with the upper surface of the joined buttedportion 3′, to thereby cool the joined butted portion 3′ from the uppersurface thereof.

[0156] Since the backward pressing roller 20 presses these joiningmembers 1 and 2, the lower surfaces of the joining members are pressedagainst the periphery of the backward supporting roller 32. Thereby,driving force in the moving direction MD can be given to the joiningmembers 1 and 2. On the other hand, in accordance with the movement ofthese joining member 1 and 2, the first to third backward pressingrollers 21, 22 and 23 integrally rotate about the axis at apredetermined position.

[0157] Next, the joining steps of the friction agitation joining methodof the first embodiment will be explained.

[0158] First, tension in a direction parallel to the joining direction(i.e., the longitudinal direction) is given to each joining member 1 and2 by tension rollers 70 and 70. This corrects the twist, curvature anddeflection of each joining member 1 and 2, and suppresses the surfacevibration of each joining member 1 and 2. The tension may be givenduring the joining process.

[0159] Furthermore, an area of the joining-direction forward side of thefirst joining member 1 covering from the widthwise intermediate portionthereof to a portion near the butted portion 3 is pressed by the firstforward pressing roller 11 from the upper surface side, and an area ofthe joining-direction forward side of the second joining member 2covering from the widthwise intermediate portion thereof to a portionnear the butted portion 3 is pressed by the second forward pressingroller 12 from the upper surface side.

[0160] The torsion of each joining member 1 and 2 is further correctedby being pressed as mentioned above, causing an adhesion of the buttedportion 3 of the joining members 1 and 2. As a result, no clearance willbe generated at the butted portion 3. Thus, both the joining members 1and 2 are moved by receiving the driving force of the forward supportingroller 31 in the adhered state.

[0161] At certain timing, the probe 42 is rotated by rotating the rotor41 of the joining tool 40. Then, the rotating probe 42 is inserted intothe butted portion 3 of the joining members 1 and 2 from the uppersurface side of thereof with the rotation axis Q inclined toward thefirst joining member side 1. Furthermore, the end face 41 a of the rotor41 is pushed against the shoulder portion 2 a of the second joiningmember 2. The insertion of the probe 42 into the butted portion 3 may beperformed from a longitudinal end of the joining members 1 and 2.Furthermore, inclining the rotation axis Q toward the first joiningmember side 1 may be performed after the insertion of the probe 42 intothe butted portion 3.

[0162] Due to the frictional heat generated in accordance with therotation of the probe 42 and the frictional heat generated by the mutualcontact between the end face 41 a of the rotor 41 and the shoulderportion 2 a of the second joining member 2, the probe-inserted portionof the butted portion 3 of the joining members 1 and 2 and therearoundare softened, the shoulder portion 2 a of the second joining member 2 isplastically deformed into an inclined surface by being pressed by theend surface 41 a of the rotor 41. Furthermore, due to this plasticdeformation, a part of the materials of the shoulder portion 2 a isfilled in the corner portion 4 a of the stepped portion 4.

[0163] The materials of the joining members 1 and 2 softened by thefrictional heat is agitated and mixed by the rotational force of theprobe 42 while the corner portion 4 a is being filled up with a part ofthe materials of the shoulder portion 2 a. In accordance with theadvance movement of the joining members 1 and 2, the softened materialsare plastically fluidized to go around the probe 42 to fill up a grooveformed behind the advancing probe 42. Then, the softened and agitatedmaterials will be cooled and solidified by the immediate loss of thefriction heat. Thus, the butted portion 3 of the joining members 1 and 2is joined as the probe 42 advances. At this time, as mentioned above,the rotation axis Q of the joining tool 40 is inclined toward the firstjoining member side 1, and a part of the materials of the shoulderportion 2 a of the second joining member 2 fills the corner portion 4 a.Therefore, the surface of the joined butted portion 3′ is formed into aninclined surface bridging the surface of the first joining member 1 andthat of the second joining member 2, as shown in FIG. 6. As shown inFIG. 6, the minute unevenness such as burrs are formed on the surface ofthe joined butted portion 3′.

[0164] While joining the butted portion 3 with the probe 42 in this way,the joining members 1 and 2 are moved and introduced between thebackward supporting roller 32 and the first to third pressing rollers21, 22 and 23. Then, an area of the joining-direction backward side ofthe first joining member 1 with respect to the probe-inserted positioncovering from the widthwise intermediate portion to a portion near thejoined butted portion 3′ is pressed by the first backward pressingroller 21 from the upper surface side, and an area of thejoining-direction backward side of the second joining member 2 withrespect to the probe-inserted position covering from the widthwiseintermediate portion to a portion near the joined butted portion 3′ ispressed by the second backward pressing roller 22 from the upper surfaceside. Furthermore, the joined butted portion 3′ is pressed by the thirdbackward pressing roller 23 from the upper surface side.

[0165] In this way, both the joining members 1 and 2 are pressed by thebackward pressing roller 20. Thereby, the twist and curvature of eachjoining member 1 and 2 are further corrected. Furthermore, since theperiphery of the third backward pressing roller 23 is formed into atapered surface, when the joined butted portion 3′ is pressed by thisthird backward pressing roller 23, the joined butted portion 3′ ispressurized. As a result, the surface is formed into a gentle inclinedsurface as shown in FIG. 7. At the same time, the minute unevennessformed on the upper surface of the joined butted portion 3′ is pressedand removed. Thereby, the surface of the joined butted portion 3′ issmoothed with the gently inclined state. Furthermore, when the joinedbutted portion 3′ is pressed, the tensile residual stress produced onthe surface of the joined butted portion 3′ is converted intocompression residual stress. Accordingly, the durability of the buttedjoining members to be obtained can be improved.

[0166] When the joining end scheduled portion of the butted portion 3 ofthe joining members 1 and 2 arrives the position of the probe 42, theprobe 42 is removed therefrom, and the joining is completed. Thus,desired joined butted joining members can be obtained by theaforementioned joining operation.

[0167] As shown in FIG. 7, where the width and the taper angle of theperiphery of the third backward pressing roller 23 are “a” and φ,respectively, the width “a” is set to be larger than the diameter D ofthe end face 41 a of the rotor 41 of the joining tool 40 (namely, a>D),and the taper angle φ is set to be smaller than the inclination angle θof the rotation axis Q to a normal line T toward the first joiningmember side 1 (namely, φ<θ). This setting makes it possible to assuredlyform a desired inclined surface of the joined butted portion 3′.Furthermore, the minute unevenness can be assuredly removed by beingpressurized.

[0168] Furthermore, since the upper surface of the joined butted portion3′ comes into contact with the cooled periphery of the third backwardpressing roller 23, the joined butted portion 3′ will be quenched fromthe upper surface. Accordingly, the joining strength improves, andfurthermore superfluous heat, which may be sometimes generated in thejoined butted portion 3′, is removed, resulting in a good joiningstatus. Furthermore, since the lower surface of the joined buttedportion 3′ comes into contact with the cooled periphery of the backwardsupporting roller 32, the butted portion 3′ will be also quenched fromthe lower surface. Accordingly, the joining strength further improves.

[0169] In the present invention, the diameter “b” of the backing roller33 is set to be equal to the diameter D of the end face 41 a of therotor 41 of the joining tool 40 or larger than D (namely, b≧D), wherethe diameter of the backing roller 33 is “b” (see FIG. 3). By settingthe diameter “b” as mentioned above, the materials of the joiningmembers softened by the frictional heat can be received from the lowersurface side assuredly.

[0170] In this friction agitation joining method, since thejoining-direction forward side of each joining member 1 and 2 withrespect to the probe inserted position is pressed and thejoining-direction backward side of each joining member 1 and 2 withrespect to the probe inserted position is pressed at the time ofjoining, the curvature and the torsion of each joining member 1 and 2can be more assuredly corrected. Then, since the joining of the buttedportion 3 is performed in this state, the generation of poor junctionsuch as joining defect or thermal distortion can be prevented moreassuredly. Furthermore, since the butted portion 3 is joined in a statein which a portion near the butted portion at the joining-directionforward side of each joining member with respect to the probe insertedposition is being pressed, the end portion of each joining member to bebutted against each other can be pressed firmly. Therefore, thegeneration of poor junction can be prevented more assuredly.

[0171] Moreover, since tension in a direction parallel to the joiningdirection WD is given to each joining member 1 and 2, configurationdefects, such as curvature, twist and deflection, can be corrected moreassuredly, and surface vibration of each joining member 1 and 2 can besuppressed. Accordingly, the generation of poor junction can beprevented more assuredly.

[0172] Furthermore, in this friction agitation joining apparatus 80,since the first forward pressing roller 11 and the second forwardpressing roller 12 are integrally connected, the structure of thesupporting jig for supporting these rollers can be simplified.

[0173] Furthermore, in the butted joining members joined by the frictionagitation joining method, since the joined butted portion 3′ is in aquenched state, high joining strength can be obtained. Moreover, sincethe upper surface of the joined butted portion 3′ is formed into aninclined surface bridging over the surface of the first joining member 1and that of the second joining member 2, the obtained butted joiningmembers can relieve the stress concentration produced in the steppedportion 4. Accordingly, outstanding reliability in strength can beobtained.

[0174] Furthermore, since the upper surface of the joined butted portion3′ is smoothened in an inclined state by removing the minute unevennesssuch as burrs by pressing them, a good surface state can be obtained.Accordingly, even in cases where the upper surface of the butted joiningmembers is painted, a film can be formed on the upper surface of thejoined butted portion 3′ in a good condition.

EXAMPLES

[0175] Next, concrete examples of the friction agitation joining methodaccording to the first embodiment will be shown.

[0176] First, a long plate-shaped first joining member made of aluminumalloy (Materials: JIS A5052-0, Dimension: length 1000 mm×Width 100mm×Thickness 2 mm) and a long plate-shaped second joining member made ofaluminum alloy (Materials: JIS A5052-O, Dimension: length 1000 mm×Width100 mm×Thickness 3 mm) were prepared.

[0177] As a joining tool 40, a tool having a rotor 41 with a probe 41 awas prepared. The diameter D of the end face 41 a of a rotor 41 was 9mm, and the protrusion length of the probe 42 from the rotor end face 41a was 2.3 mm. The probe 42 had an M3 screw axial portion.

[0178] As forward pressing rollers 10, the rollers as shown in FIGS. 8Aand 8B were prepared, while as backward pressing rollers 20, the rollersas shown in FIGS. 8C to 8E were prepared. The structure of each rollerwas as follows.

[0179] The forward pressing roller 10A shown in FIG. 8A is the samecolumn-shaped member as the conventional one, and is disposed so as tocover the butted portion.

[0180] The forward pressing roller 10B shown in FIG. 8B has the samestructure as the roller 10 of the first embodiment.

[0181] The backward pressing roller 20C shown in FIG. 8C has the samecolumnar-shape member as the conventional one.

[0182] The backward pressing roller 20D shown in FIG. 8D has the samestructure as the roller 20 of the first embodiment.

[0183] The backward pressing roller 20E shown in FIG. 8E comprises afirst backward pressing roller 21, a second backward pressing roller 22and a columnar connecting axial portion 24 having a diameter smallerthan that of the second backward pressing roller 22. The first backwardpressing roller 21 and the second backward pressing roller 22 areintegrally connected by the columnar connecting axial portion 24. Inother words, the backward pressing roller 20E does not have a thirdbackward pressing roller for pressing the joined butted portion 3′. Thisbackward pressing roller 20E is arranged so that the first and secondbackward pressing rollers 21 and 22 are disposed besides the joinedbutted portion.

Example 1

[0184] The side edge of the first joining member 1 and that of thesecond joining member 2 were butted against each other with the lowersurfaces thereof being flush with each other. Then, the butted portion 3was joined along the entire length thereof by the joining method of thefirst embodiment. In this joining, the roller 10B shown in FIG. 8B wasused as the forward pressing roller, and the roller 20D shown in FIG. 8Dwas used as the backward pressing roller. The joining was performedunder the following conditions: the rotating speed of the rotor 41 ofjoining tool 40 was 1,000 rpm; the joining rate was 700 mm/min; theinclination angle θ of the rotation axis Q of the joining tool 40 towardthe first joining member 1 was 5°.

Example 2

[0185] The forward pressing roller 10B shown in FIG. 8B and the backwardpressing roller 20C shown in FIG. 8C were used. The butted portion 3 ofthe joining members 1 and 2 was joined along the entire length thereof.Other joining conditions were the same as the aforementioned example 1.

Example 3

[0186] The forward pressing roller 10A shown in FIG. 8A and the backwardpressing roller 20D shown in FIG. 8D were used. The butted portion 3 ofthe joining members 1 and 2 was joined along the entire length thereof.Other joining conditions were the same as the aforementioned example 1.

Example 4

[0187] The forward pressing roller 10A shown in FIG. 8A and the backwardpressing roller 20E shown in FIG. 8E were used. The butted portion 3 ofthe joining members 1 and 2 was joined along the entire length thereof.Other joining conditions were the same as the aforementioned example 1.

Comparative Example

[0188] The forward pressing roller 10A shown in FIG. 8A and the backwardpressing roller 20C shown in FIG. 8C were used. The butted portion 3 ofthe joining members 1 and 2 was joined along the entire length thereof.Other joining conditions were the same as the aforementioned example 1.

[0189] About the butted joining members obtained by the aforementionedexamples 1-4 and the comparative example, the surface state of thejoined butted portion was investigated with the naked eye, and theamount of thermal distortion was investigated. TABLE 1 Surface stateForward Backward of the joined pressing pressing butted Thermal rollerroller portion(*) distortion Example 1 Roller shown Roller shown ◯ 3 mmin FIG. 8B in FIG. 8D Example 2 Roller shown Roller shown Δ 3 mm in FIG.8B in FIG. 8C Example 3 Roller shown Roller shown ◯ 5 mm in FIG. 8A inFIG. 8D Example 4 Roller shown Roller shown Δ 5 mm in FIG. 8A in FIG. 8EComparative Roller shown Roller shown Δ 10 mm Example in FIG. 8A in FIG.8C

[0190] About the amount of thermal distortion in Table 1, the amount ofthe maximum curvature of the obtained butted joining members disposed ona flat surface is shown as the amount of thermal distortion.

[0191] As shown in this table, in the butted joining members obtained bythe comparative example, the amount of thermal distortion was 10 mm, anda large thermal distortion was generated. On the other hand, in thebutted joining members obtained by the examples 1 to 4, the amount-ofthermal distortion was 5 mm or less, and the generation of thermaldistortion was suppressed. Especially in the butted joining members ofexamples 1 and 2, the amount of thermal distortion was 3 mm, and thegeneration of thermal distortion was further suppressed.

[0192] Furthermore, in the butted joining members obtained by thecomparative example, the non-joined portion was generated in the joinedbutted portion, and the poor joining was generated. On the other hand,in the butted joining members obtained by the examples 1 to 4, anon-joined portion was not generated, and the joining state was good.

[0193] Furthermore, in the butted joining members obtained by theexamples 2, 4 and the comparative example, minute unevenness such asburrs were formed on the upper surface of the joined butted portion. Tothe contrary, in the butted joining members obtained by the examples 1and 3, such minute unevenness was not formed on the upper surface of thejoined butted portion. This surface was smoothened with an inclinedstate, and the surface state was very good.

[0194] Second Embodiment

[0195] FIGS. 9 to 16 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining method according to the second embodimentof the present invention. In these figures, the same reference numeralis allotted to the same component as in the aforementioned firstembodiment. Hereinafter, this second embodiment will be explained byfocusing on the differences between the first embodiment and the secondembodiment.

[0196] In this second embodiment, as shown in FIG. 9, the forwardpressing roller 10 is divided into the first forward pressing roller 11and the second forward pressing roller 12. That is, the first forwardpressing roller 11 and the second forward pressing roller 12 areseparate members. The outer diameter of first forward pressing roller 11and that of the second forward pressing roller 12 have the samedimension.

[0197] In FIG. 9, “50” denotes a thermometry apparatus (e.g., radiationthermometer) for measuring the surface temperature of the joined buttedportion 3′ of the joining members 1 and 2. This thermometry apparatus 50is arranged between the probe inserted position at the upper surfaceside of the joining members 1 and 2 and the third backward pressingroller 23.

[0198] In FIG. 10, “60 a” is an inclination angle changing apparatus forthe first forward pressing roller 11. As shown in FIG. 11, thisinclination angle changing apparatus 60 a is for changing theinclination angle α1 of the axis P1 of the first forward pressing roller11 within a plane parallel to the upper surface of the first joiningmember 1 with respect to the butting-direction N of the first joiningmember 1. Furthermore, as shown in FIG. 14, this inclination anglechanging apparatus 60 a also has a function for changing the inclinationangle β1 of the axis P1 of the first forward pressing roller 11 within aplane perpendicular to the joining-direction WD with respect to thebutting-direction N of the first joining member 1. To this inclinationangle changing apparatus 60 a, the first forward pressing roller 11 isconnected. Therefore, by operating this inclination angle changingapparatus 60 a, the inclination angle α1 and the inclination angle β1can be changed, respectively.

[0199] In FIG. 10, “61 a” denotes a controller for the first forwardpressing roller 11. This controller 61 a is for controlling operation ofthe inclination angle changing apparatus 60 a based on the measuredvalue obtained by the thermometry apparatus 50, as shown in FIG. 11. Tothis controller 61 a, the thermometry apparatus 50 is connected.Furthermore, to this controller 61 a, the inclination angle changingapparatus 60 a is connected.

[0200] In FIG. 10, “60 b” is an inclination angle changing apparatus forthe second forward pressing roller 12. As shown in FIG. 11, thisinclination angle changing apparatus 60 b is for changing theinclination angle α2 of the axis P2 of the second forward pressingroller 12 within a plane parallel to the upper surface of the secondjoining member 2 with respect to the butting-direction N of the secondjoining member 2. Furthermore, as shown in FIG. 14, this inclinationangle changing apparatus 60 b also has a function for changing theinclination angle β2 of the axis P2 of the second forward pressingroller 12 within a plane perpendicular to the joining-direction WD withrespect to the butting-direction N of the second joining member 2. Tothis inclination angle changing apparatus 60 b, the second forwardpressing roller 12 is connected. Therefore, by operating thisinclination angle changing apparatus 60 b, the inclination angle α2 andthe inclination angle β2 can be changed, respectively.

[0201] In FIG. 10, “61 b” denotes a controller for the second forwardpressing roller 12. This controller 61 b is for controlling operation ofthe inclination angle changing apparatus 60 b based on the measuredvalue obtained by the thermometry apparatus 50, as shown in FIG. 11. Tothis controller 61 b, the thermometry apparatus 50 is connected.Furthermore, to this controller 61 b, the inclination angle changingapparatus 60 b is connected.

[0202] In this friction agitation joining apparatus 80, as shown in FIG.9, the forward supporting roller 31 is divided into the first forwardsupporting roller 31 a and the second forward supporting roller 31 b.That is, the first forward supporting roller 31 a and the second forwardsupporting roller 31 b are separate members. The outer diameter of firstforward supporting roller 31 a and that of the second forward supportingroller 31 b have the same dimension. By the first forward supportingroller 31 a, the joining-direction forward side of the first joiningmember 1 relative to the probe inserted position is supported from thelower surface. Furthermore, by the second forward supporting roller 31b, the joining-direction forward side of the second joining member 2relative to the probe inserted position is supported from the lowersurface.

[0203] In FIG. 10, “65 a” is an inclination angle changing apparatus forthe first forward supporting roller 31 a. As shown in FIG. 12, thisinclination angle changing apparatus 65 a is for changing theinclination angle γ1 of the axis S1 of the first forward supportingroller 31 a within a plane parallel to the lower surface of the firstjoining member 1 with respect to the butting-direction N of the firstjoining member 1. To this inclination angle changing apparatus 65 a, thefirst forward supporting roller 31 a is connected. Therefore, byoperating this inclination angle changing apparatus 65 a, theinclination angle γ1 can be changed.

[0204] In FIG. 10, “65 b” is an inclination angle changing apparatus forthe second forward supporting roller 31 b. As shown in FIG. 12, thisinclination angle changing apparatus 65 b is for changing theinclination angle γ2 of the axis S2 of the second forward supportingroller 31 b within a plane parallel to the lower surface of the secondjoining member 2 with respect to the butting-direction N of the secondjoining member 2. To this inclination angle changing apparatus 65 b, thesecond forward supporting roller 31 b is connected. Therefore, byoperating this inclination angle changing apparatus 65 b, theinclination angle γ2 can be changed.

[0205] In this friction agitation joining apparatus 80, the firstforward pressing roller 11 is arranged as shown in FIG. 13 by operatingthe inclination angle changing apparatus 60 a as follows. That is, thefirst forward pressing roller 11 is arranged in a state that one endthereof at the butted portion side 3 of the first joining member 1 ispositioned at a joining-direction forward position with respect to theother end thereof and that the axis P1 of this roller 11 is inclinedrelative to the butting-direction N of the first joining member 1 withina plane parallel to the upper surface of the first joining member 1. Byarranging this first forward pressing roller 11 as mentioned above,force in the butting direction N of the first joining member 1 is givento the first joining member 1 in accordance with the movement of thefirst joining member 1. Furthermore, in this friction agitation joiningapparatus 80, the second forward pressing roller 12 is arranged byoperating the inclination angle changing apparatus 60 b as follows. Thatis, the second forward pressing roller 12 is arranged in a state thatone end thereof at the butted portion side 3 of the second joiningmember 2 is positioned at a joining-direction forward position withrespect to the other end thereof and that the axis P2 of this roller 12is inclined relative to the butting-direction N of the second joiningmember 2 within a plane parallel to the upper surface of the secondjoining member 2. By arranging this second forward pressing roller 12 asmentioned above, force in the butting direction N of the second joiningmember 2 is given to the second joining member 2 in accordance with themovement of the second joining member 2. Accordingly, in accordance withthe movement of the joining members 1 and 2, both the joining members 1and 2 come into strong contact with each other at the butted portion 3,and moves in the predetermined direction MD in the contact state.

[0206] In this friction agitation joining apparatus 80, the firstforward supporting roller 31 a is arranged as shown in FIG. 13 byoperating the inclination angle changing apparatus 65 a as follows. Thatis, the first forward supporting roller 31 a is arranged in a state thatone end thereof at the butted portion side 3 of the first joining member1 is positioned at a joining-direction forward position with respect tothe other end thereof and that the axis S1 of this roller 31 is inclinedrelative to the butting-direction N of the first joining member 1 withina plane parallel to the lower surface of the first joining member 1.Similarly, the second forward supporting roller 31 b is arranged byoperating the inclination angle changing apparatus 65 b as follows. Thatis, the second forward supporting roller 31 b is arranged in a statethat one end thereof at the butted portion side 3 of the second joiningmember 2 is positioned at a joining-direction forward position withrespect to the other end thereof and that the axis S2 of this roller 31b inclined relative to the butting-direction N of the second joiningmember 2 within a plane parallel to the lower surface of the secondjoining member 2. By arranging the first and second forward supportingrollers 31 a and 31 b as mentioned above, both the joining members 1 and2 come into strong contact with each other at the butted portion 3.

[0207] In this friction agitation joining apparatus 80, the firstforward pressing roller 11 is arranged as shown in FIG. 15 by operatingthe inclination angle changing apparatus 60 a as follows. That is, thefirst forward pressing roller 11 is arranged in a state that one endthereof at the butted portion side 3 of the first joining member 1 ispositioned upper than the other end thereof and that the axis P1 of thisroller 11 is inclined relative to the butting-direction N of the firstjoining member 1 within a plane perpendicular to the joining directionWD. In this state, the first forward pressing roller 11 presses thefirst joining member 1. Similarly, the second forward pressing roller 12is arranged by operating the inclination angle changing apparatus 60 bas follows. That is, the second forward pressing roller 12 is arrangedin a state that one end thereof at the butted portion side 3 of thesecond joining member 2 is positioned upper than the other end thereofand that the axis P2 of this roller 12 is inclined relative to thebutting-direction N of the second joining member 2 within a planeperpendicular to the joining direction WD. In this state, the secondforward pressing roller 12 presses the second joining member 2.

[0208] As shown in FIG. 16, in this friction agitation joiningapparatus, the backward supporting roller 32 is divided into the firstbackward supporting roller 32 a and the second backward supportingroller 32 b. The outer diameter of the first backward supporting roller32 a and that of the second backward supporting roller 32 b have thesame dimension. The joining-direction backward side of the first joiningmember 1 with respect to the probe inserted position is supported by thefirst backward supporting roller 32 a from the lower surface sidethereof, while the joining-direction backward side of the second joiningmember 2 with respect to the probe inserted position is supported by thesecond backward supporting roller 32 b from the lower surface sidethereof.

[0209] In this second embodiment, the joining operation is performed asfollows. The butted portion 3 is joined with the probe 42 by moving boththe joining members 1 and 2 in the predetermined direction MD whilemeasuring the surface temperature of the joined butted portion 3′ of thejoining members 1 and 2.

[0210] In cases where the surface temperature of the joined buttedportion 3′ is higher than or lower than the predetermined temperature,poor junction such as joining defect and thermal distortion generateeasily. Therefore, if it is discriminated that the surface temperatureof the joined butted portion 3′ is higher than or lower than thepredetermined temperature during the joining, at least one of theinclination angle changing apparatuses 60 a and 60 b is operated via thecontroller 61 a and 61 b based on the measured value obtained thethermometry apparatus 50 in order to change at least one of theinclination angles β1 or β2. Thereby, the press force from the roller tobe received by the joining members 1 and 2 changes in the buttingdirection N. As a result, generation of poor junction can be preventedassuredly. This changing operation of the inclination angle β1 and β2 isperformed automatically. Thus, in this second embodiment, joining can beperformed while preventing generation of poor junction, and thereforepoor joining prevention work can be performed efficiently.

[0211] Furthermore, in this second embodiment, since the butted portion3 is joined with both joining members 1 and 2 firmly adhered, a firmlyjoined butted portion 3′ can be obtained. Also, the fault that thebutted portion 3 detaches during the movement of the joining members 1and 2 can be prevented.

[0212] Furthermore, since the forward pressing roller 10 is divided intothe first forward pressing roller 11 and the second forward pressingroller 12, each joining member 1 and 2 can be pressed firmly even if thethickness of each joining member 1 and 2 fluctuates in the longitudinaldirection.

[0213] Furthermore, since the backward supporting roller 32 is dividedinto the first backward supporting roller 32 a and the second backwardsupporting roller 32 b, the design freedom degree of the backwardsupporting roller 32 can be increased. Accordingly, the meanderingmovement of the joining members 1 and 2 can be prevented by changing themutual position of the first backward supporting roller 32 a and thesecond backward supporting roller 32 b or changing the circumferentialspeed thereof. Furthermore, straightening effect to the configurationdefect of each joining member 1 and 2 can be increased.

[0214] In this second embodiment, as a characteristic regarding thejoining state of the joined butted portion 3′, the surface temperatureof the butted portion 3′ is exemplified. However, in the presentinvention, the characteristic regarding the joining state may be, forexample, the surface residual stress of the butted portion 3′.

[0215] However, the present invention is not limited to thoserepresented by the aforementioned first and second embodiments, andallow various settings.

[0216] For example, the backward pressing roller 20 may be divided intoa first backward pressing roller 21, a second backward pressing roller22 and a third backward pressing roller 23.

[0217] Furthermore, the forward pressing roller 10 and/or the backwardpressing roller 20 may be constituted such that they function as adriving roller for moving the joining members 1 and 2 in thepredetermined direction MD or they are provided withcircumferential-speed controlling mechanism.

[0218] Furthermore, in the friction agitation joining method accordingto the present invention, the butted portion 3 may be joined by movingthe rotating probe 42 inserted into the butted portion 3 of the joiningmembers 1 and 2 along the butted portion 3 in a state in which theposition of the joining members 1 and 2 is fixed. In this case, themoving direction of the probe coincides with the joining direction.

[0219] Third Embodiment

[0220] FIGS. 17 to 21 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining method according to the third embodiment ofthe present invention. In these figures, the same reference numeral isallotted to the same component as in the aforementioned firstembodiment. Hereinafter, this third embodiment will be explained byfocusing on the differences between the first embodiment and the thirdembodiment.

[0221] In this third embodiment, the friction agitation joiningapparatus 80 is equipped with a heating roller 91 as a heating device.This heating roller 91 is constituted by a backing roller 33 having thefollowing structure. The structure of the backing roller 33 will beexplained as follows. As shown in FIG. 18, at the peripheral surfaceportion of the longitudinal intermediate portion of the backing roller33, an electric heater 91 a as heating source is embedded along theentire circumference thereof. As shown in FIG. 17, the electric powersupplying cord 91 b for supplying electric power to the electric heater91 a is connected to the electric heater 91 a. This backing roller 33 ismade of heat-resisting materials that can withstand heat generated bythe electric heater 91 a. By supplying electric power to this electricheater 91 a to generate heat, the periphery of the backing roller 33 isheated.

[0222] In this third embodiment, the forward pressing roller 10 isdivided into the first forward pressing roller 11 and the second forwardpressing roller 12 in the same manner as in the second embodiment, asshown in FIG. 17. That is, the first forward pressing roller 11 and thesecond forward pressing roller 12 are members separated each other. Theouter diameter of the first forward pressing roller 11 and that of thesecond forward pressing roller 12 are set to have the same dimension.

[0223] Furthermore, as shown in FIG. 17, the backward pressing roller 20is not equipped with a third backward pressing roller, and divided intothe first backward pressing roller 21 and the second backward pressingroller 22. That is, the first backward pressing roller 21 and thebackward pressing roller 22 are members separated from each other. Theouter diameter of the first backward pressing roller 21 and that of thesecond backward pressing roller 22 are set to have the same dimension.

[0224] In this third embodiment, the joining operation is performed asfollows. That is, in advance, the periphery of backing roller 33 isheated by the electric heater 91 a. Then, during the joining, the lowersurface of the joining members 1 and 2 is heated by bringing the heatedperiphery of the backing roller 33 into contact with the lower surfaceof the butted portion 3 of the joining members 1 and 2 at the probeinserted position. As a result, the heat of the periphery of the backingroller 33 is conducted to the lower surface of joining members 1 and 2,and then the conducted heat is conducted from the lower surface in thethickness direction. Thereby, the portion near the lower surface in thethickness direction of the joining members 1 and 2 becomes hightemperature state. In FIGS. 18 and 20, “Y” denotes a portion of thejoining members 1 and 2 in a high temperature state. In the presentinvention, it is preferable to heat the lower surface so that thetemperature of the lower surface of the joining members 1 and 2 fallswithin the range of from 400° to 500° because of the following reasons.If the temperature of the lower surface is less than 400° C., there is apossibility that the mixing of materials cannot be performed well due toinsufficient heating. On the other hand, if it exceeds 500° C., there isa possibility that the joining members 1 and 2 may be melt due tooverheating.

[0225] In a state in which the heated periphery of the backing roller 33contacts the lower surface of the joining members 1 and 2, both joiningmembers 1 and 2 are moved in a predetermined direction MD. As a result,in accordance with the movement of the joining member 1 and 2, thebutted portion 3 is joined by the probe 42 at the probe insertedposition.

[0226] In this third embodiment, since the lower surface of the probeinserted position of the butted portion 3 of the joining members 1 and 2is contacted by the heated backing roller 33 and therefore heated, theportion near the lower surface in the thickness direction of the joiningmembers 1 and 2 is in a high temperature state. Accordingly, thematerials between the tip of the probe 42 and the lower surfaces of thejoining members 1 and 2 can be softened very quickly, resulting insufficient mixing of the materials. Accordingly, the generating of theroot remaining portion R (see FIG. 31) can be prevented, and as shown inFIG. 21, the butted portion 3 can be joined along the entire thicknesslength. Accordingly, according to this friction agitation joiningmethod, even if the thickness dimension of the joining member 1 and 2fluctuates in the longitudinal direction, the generation of the rootremaining portion can be prevented assuredly, resulting in improvedjoining strength.

[0227] Furthermore, in this friction agitation joining method, since thejoining is performed while heating the lower surface of the probeinserted position of the butted portion 3 of the joining members 1 and 2by the periphery of the backing roller 33, the joining operation can beperformed well and the heating can be performed efficiently.

[0228] In the present invention, the joining may be performed whileheating the lower surface of the joining-direction forward side of theprobe inserted position of the joining members 1 and 2 by bringing theheated periphery of the heating roller 91 into contact with the lowersurface.

[0229] Fourth Embodiment

[0230]FIGS. 22 and 23 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining method according to the fourth embodimentof the present invention. In these figures, the same reference numeralis allotted to the same component as in the aforementioned firstembodiment. Hereinafter, this fourth embodiment will be explained byfocusing on the differences between the third embodiment and the fourthembodiment.

[0231] In this fourth embodiment, the friction agitation joiningapparatus 80 is equipped with a laser irradiation heating apparatus 92as a heating apparatus. As shown in FIG. 22, this laser irradiationheating apparatus 92 is disposed at the lower surface side of theportion near the probe inserted position of the joining-directionforward side of the joining members 1 and 2. On the other hand, thebacking roller 33 has no built-in electric heater.

[0232] This laser irradiation heating apparatus 92 is equipped with anozzle 92 b for injecting a laser 92 a. This nozzle 92 b is disposedwith the injection tip facing up.

[0233] In this fourth embodiment, a laser 92 a is injected from theinjection tip of the nozzle 92 b at the time of joining, and this laser92 a irradiates the lower surface of the butted portion 3 of the joiningmembers 1 and 2 at the joining-direction forward side of the probeinserted position to heat the lower surface. Then, the heat conducts inthe thickness direction from the lower surface. Thereby, the portionnear the lower surface of joining members 1 and 2 will become high intemperature (“Y” denotes the portion).

[0234] While irradiating the laser 92 a at the lower surface of joiningmembers 1 and 2, the joining members 1 and 2 are moved in thepredetermined direction MD. In accordance with the movement of thejoining members 1 and 2, the butted portion 3 is joined by the probe 42at the probe inserted position.

[0235] In this fourth embodiment, when the high temperature portion Y ofthe joining members 1 and 2 reaches the probe inserted position inaccordance with the movement of the joining members 1 and 2, thematerials between the tip of the probe 42 and the lower surfaces of thejoining members 1 and 2 softens very quickly, resulting in sufficientmixture of the materials. Accordingly, the generation of the rootremaining portion R (see FIG. 31) can be prevented.

[0236] In the present invention, in cases where there are no obstructionsuch as a backing roller 33 at the lower surface side of the buttedportion 3 of the joining members 1 and 2 at the probe inserted position,the joining may be performed while heating the lower surface of theprobe inserted position of the joining members 1 and 2 at the buttedportion 3 by irradiating the laser 92 a.

[0237] Fifth Embodiment

[0238]FIGS. 24 and 25 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining method according to the fifth embodiment ofthe present invention. In these figures, the same reference numeral isallotted to the same component as in the aforementioned firstembodiment. Hereinafter, this fifth embodiment will be explained byfocusing on the differences between the third embodiment and the fifthembodiment.

[0239] In the fifth embodiment, the friction agitation joining apparatus80 is equipped with a high frequency induction heating apparatus 93 as aheating apparatus. This high frequency induction heating apparatus 93 isdisposed at the lower surface side of the portion near the probeinserted position of the joining-direction forward side of the joiningmembers 1 and 2. On the other hand, the backing roller 33 has nobuilt-in electric heater.

[0240] This high frequency induction heating apparatus 93 is equippedwith an induction coil 93 a. To this induction coil 93 a, a highfrequency power source (not shown) is connected. As shown in FIG. 25,this induction coil 93 a is disposed at the lower surface of the joiningmembers 1 and 2 in contact with the lower surface or near the lowersurface so as to bridge the butted portion 3.

[0241] In this fifth embodiment, a high frequency current is made topass through the induction coil 93 a at the time of joining to therebygenerate an induced current at the lower surface of the joining members1 and 2. Thereby, the lower surface is heated.

[0242] While generating an induced current at the lower surface ofjoining members 1 and 2, the joining members 1 and 2 are moved in thepredetermined direction MD. In accordance with the movement of thejoining members 1 and 2, the butted portion 3 is joined by the probe 42at the probe inserted position.

[0243] In this fifth embodiment, when the high temperature portion Y ofthe joining members 1 and 2 reaches the probe inserted position inaccordance with the movement of the joining members 1 and 2, thematerials between the tip of the probe 42 and the lower surfaces of thejoining members 1 and 2 softens very quickly, resulting in sufficientmixture of the materials. Accordingly, the generation of the rootremaining portion R (see FIG. 31) can be prevented.

[0244] In the present invention, in cases where there are no obstructionsuch as a backing roller 33 at the lower surface side of the buttedportion 3 of the joining members 1 and 2 at the probe inserted position,the joining may be performed while heating the lower surface of theprobe inserted position of the joining members 1 and 2 at the buttedportion 3 by disposing an induction coil 93 a at the lower surface atthe probe inserted position to thereby generate an induced current inthe lower surface.

[0245] Sixth Embodiment

[0246] FIGS. 26 to 28 are drawings for explaining a friction agitationjoining method, a method for manufacturing of butted joining members anda friction agitation joining method according to the sixth embodiment ofthe present invention. In these figures, the same reference numeral isallotted to the same component as in the aforementioned firstembodiment. Hereinafter, this sixth embodiment will be explained byfocusing on the differences between the third embodiment and the sixthembodiment.

[0247] In the sixth embodiment, the thickness t1 of the first joiningmember 1 is 3 mm or less, concretely, t1 is 1 mm, where the relationbetween the thickness t1 of the first joining member 1 and the thicknesst2 of the second joining member 2 is given by the inequality: t2>t1 (seeFIG. 28).

[0248] The friction agitation joining apparatus 80 is equipped with afriction agitation joining sub-joining tool 45 for joining the rootremaining portion R (see FIG. 31). Hereinafter, the aforementionedjoining tool 40 for joining the butted portion 3 of the joining members1 and 2 from the upper surface side, the rotor 41 and the probe 42 willbe referred to as a “main joining tool”, a “main rotor” and a “mainprobe,” respectively, for an explanation purpose.

[0249] The sub-joining tool 45 is provided with a column-shapedsub-rotor 46 having a larger diameter and a pin-shaped sub-probe 47having a smaller diameter. The sub-probe 47 is integrally projected fromthe rotational center of the end face 46 a of the sub-rotor 46 along therotation-axis S.

[0250] The length of the sub-probe 47 is set to be much shorter thanthat of the main probe 42 of the main joining tool 40. It is especiallypreferable that the length falls within the range of from 0.1 mm to 0.5mm. The other structure of this sub-joining tool 45 is the same as theaforementioned main joining tool 40.

[0251] This sub-joining tool 45 is disposed at the portion near thejoining-direction forward side of the main probe inserted position ofthe lower surface side of the joining members 1 and 2 with the sub-probe47 facing up. In this sixth embodiment, the rotating sub-probe 47 of thesub-joining tool 45 is inserted into the portion at thejoining-direction forward side near the main probe inserted positionfrom the lower surface side. Preferably, the end face 46 of thesub-rotor 46 is pressed against the lower surface of the joining members1 and 2. Then, in this state, both joining members 1 and 2 are moved ina predetermined direction MD so that the main probe 42 and the sub-probe47 advance the butted portion 3.

[0252] At this time, it is preferable that the insertion depth δ of thesub-probe 47 into the butted portion 3 from the lower surface (see FIG.28) falls within the range of from 0.1 to 0.5 mm because of thefollowing reasons. If the insertion depth δ of the sub-probe 47 is lessthan 0.1 mm, there is a possibility that an insertion depth may beinsufficient and therefore the root remaining portion may remain. On theother hand, if the insertion depth δ of the sub-probe 47 exceeds 0.5 mm,the force to be required for moving the joining members 1 and 2 becomeslarge, which in turn becomes difficult to perform the moving operationof the joining members 1 and 2. Accordingly, it is preferable that theinsertion depth δ of the sub-probe 47 falls within the range of from 0.1to 0.5 mm.

[0253] In accordance with the movement of the joining members 1 and 2,the portion near the joining-direction forward side of the probeinserted position at the butted portion 3 of the joining members 1 and 2is joined shallowly by the sub-joining tool 47 of the sub-probe 45.When, the joined portion reaches the main probe inserted position of themain joining tool 40, the butted portion 3 is joined in the entirethickness direction by the main probe 42. Accordingly, the generation ofthe root remaining portion R (see FIG. 31) can be prevented.

[0254] In the present invention, as shown by the hypothetical line inFIG. 27, the joining may be performed in a state in which the rotatingsub-probe 47 of the sub-joining tool 45 may be inserted into the joinedbutted portion 3′ of the joining members 1 and 2 from the lower surfaceside. In cases where there are no obstruction such as a backing roller33 at the lower surface side of the butted portion 3 of the joiningmembers 1 and 2 at the main probe inserted position, the joining may beperformed while inserting a rotating sub-probe 47 of the sub-joiningtool 45 into the lower surface of the main probed inserted position ofthe joining members 1 and 3 at the butted portion 3.

[0255] Furthermore, in the friction agitation joining method accordingto the present invention, the butted portion 3 may be joined by movingthe rotating probe 42 inserted into the butted portion 3 of the joiningmembers 1 and 2 along the butted portion 3 in a state in which theposition of the joining members 1 and 2 is fixed. In this case, themoving direction of the probe coincides with the joining direction.

[0256] Next, concrete examples of the friction agitation joining methodaccording to the third to sixth embodiments will be shown.

Example 5

[0257] Long plate-shaped first joining members made of aluminum alloy(Materials: JIS A6063-T5, Thickness: 1 mm) and long plate-shaped secondt joining members made of aluminum alloy (Materials: JIS A6063- T5,Thickness: 2 mm) were prepared. Then, side edges of the joining members1 and 2 were butted against each other with the lower surfaces beingflush with each other, and the butted portion 3 thereof was joined alongthe entire length by the aforementioned joining method according to thethird embodiment.

Example 6

[0258] The butted portion 3 of the joining members 1 and 2 was joinedalong the entire length by the aforementioned joining method accordingto the fourth embodiment. Other joining conditions are the same as thoseof the aforementioned fifth example.

Example 7

[0259] The butted portion 3 of the joining members 1 and 2 was joinedalong the entire length by the aforementioned joining method accordingto the fifth embodiment. Other joining conditions are the same as thoseof the aforementioned fifth example.

Example 8

[0260] The butted portion 3 of the joining members 1 and 2 was joinedalong the entire length by the aforementioned joining method accordingto the sixth embodiment. In this joining, the insertion depth δ of thesub-probe 47 of the sub-joining tool 45 was set as 0.1 mm. Other joiningconditions are the same as those of the aforementioned fifth example.

[0261] About the butted joining members obtained in the above examples 5to 8, each cross-section was observed by using a microscope, and thejoining state was evaluated. As a result, no root remaining portion canbe found in any butted joining member. This result shows that the joinedbutted joining members have high bonding strength and outstandingstrength reliability.

[0262] Effects of the present invention will be summarized as follows.

[0263] According to friction-agitation-joining method of the firstaspect of the present invention, by pressing joining-direction forwardsides of the first joining member and the second joining member withrespect to a probe inserted position from the upper surface sides by afirst forward pressing roller and a second forward pressing roller,respectively, it is possible to prevent a fault such as an unexpectedmovement of each joining member during the joining and also to correctthe configuration defect of each joining member such as torsion orcurvature. Furthermore, performing the joining process in this state canprevent the generation of poor Junction such as joint defect or thermaldistortion, resulting in high quality joined butted joining members.

[0264] According to the friction agitation joining method of the secondaspect of the present invention, the same effects as in the first aspectof the present invention can be obtained.

[0265] According to the friction agitation joining method of the thirdaspect of the present invention, generation of poor junction can beprevented or suppressed, and therefore butted joining members with highquality can be obtained.

[0266] According to the friction agitation joining method of the fourthaspect of the present invention, since the butted portion is joinedwhile heating the lower surface of the butted portion of the joiningmembers at the probe inserted position or the joining-direction forwardside, generating of the root remaining portion can be prevented, andtherefore joined butted joining members with high joining strength canbe obtained.

[0267] According to the friction agitation joining method of the fifthaspect of the present invention, since the butted portion is joined bymoving the joining members with respect to the main probe and thesub-probe so that the probes advance along the butted portion in a statein which a rotating sub-probe of the sub-joining tool is inserted intothe butted portion of the joining members or the joined butted portion,generation of root remaining portion can be prevented, and thereforebutted joining members having high joining strength can be obtained.

[0268] According to the method for manufacturing butted joining membersof the sixth aspect of the present invention, the same effects as in thefirst aspect of the present invention can be obtained.

[0269] According to the method for manufacturing butted joining membersof the seventh aspect of the present invention, the same effects as inthe second aspect of the present invention can be obtained.

[0270] According to the method for manufacturing butted joining membersof the eighth aspect of the present invention, the same effects as inthe third aspect of the present invention can be obtained.

[0271] According to the method for manufacturing butted joining membersof the ninth aspect of the present invention, the same effects as in thefourth aspect of the present invention can be obtained.

[0272] According to the method for manufacturing butted joining membersof the tenth aspect of the present invention, the same effects as in thefifth aspect of the present invention can be obtained.

[0273] According to the friction agitation joining apparatus of theeleventh aspect of the present invention, the friction agitation joiningmethod of the first aspect of the present invention or the method formanufacturing butted joining members of the sixth aspect of the presentinvention can be performed efficiently.

[0274] According to the friction agitation joining apparatus of thetwelfth aspect of the present invention, the friction agitation joiningmethod of the second aspect of the present invention or the method formanufacturing butted joining members of the seventh aspect of thepresent invention can be performed efficiently.

[0275] According to the friction agitation joining apparatus of thethirteenth aspect of the present invention, the friction agitationjoining method of the third aspect of the present invention or themethod for manufacturing butted joining members of the eighth aspect ofthe present invention can be performed efficiently.

[0276] According to the friction agitation joining apparatus of thefourteenth aspect of the present invention, the friction agitationjoining method of the fourth aspect of the present invention or themethod for manufacturing butted joining members of the ninth aspect ofthe present invention can be performed efficiently.

[0277] According to the friction agitation joining apparatus of thefifteenth aspect of the present invention, the friction agitationjoining method of the fifth aspect of the present invention or themethod for manufacturing butted joining members of the tenth aspect ofthe present invention can be performed efficiently.

[0278] The terms and expressions which have been employed herein areused as terms of description and not of limitation, and there is nointent, in the use of such terms and expressions, of excluding any ofthe equivalents of the features shown and described or portions thereof,but it is recognized that various modifications are possible within thescope of the invention claimed.

INDUSTRIAL APPLICABILITY

[0279] A friction agitation joining method, a method for manufacturingjoined butted members and a friction agitation joining apparatus arepreferably used for manufacturing metal plate-shaped members used as,for example, flooring materials, wall materials and ceiling materialsfor transporting device such as automobiles, aircrafts and railroadvehicles.

1. A friction agitation joining method for joining a first joiningmember (1) and a second joining member (2) butted against each otherwith a level difference formed at upper surface sides thereof byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), wherein joining of said butted portion (3) isperformed while pressing joining-direction forward sides of said firstjoining member (1) and said second joining member (2) with respect to aprobe inserted position from said upper surface sides by a first forwardpressing roller (11) and a second forward pressing roller (11),respectively.
 2. A friction agitation joining method for joining a firstjoining member (1) and a second joining member (2) butted against eachother with a level difference formed at upper surface sides thereof byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), wherein joining of said butted portion (3) isperformed while pressing joining-direction backward sides of said firstjoining member (1) and said second joining member (2) with respect to aprobe inserted position from said upper surface sides by a firstbackward pressing roller (21) and a second backward pressing roller(22), respectively.
 3. A friction agitation joining method for joining afirst joining member (1) and a second joining member (2) butted againsteach other with a level difference formed at upper surface sides thereofby relatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), wherein joining of said butted portion (3) isperformed while pressing joining-direction forward sides of said firstjoining member (1) and said second joining member (2) with respect to aprobe inserted position from said upper surface sides by a first forwardpressing roller (11) and a second forward pressing roller (11),respectively, and pressing joining-direction backward sides of saidfirst joining member (1) and said second joining member (2) with respectto a probe inserted position from said upper surface sides by a firstbackward pressing roller (21) and a second backward pressing roller(22), respectively.
 4. The friction agitation joining method as recitedin claim 1 or 3, wherein said joining of said butted portion (3) isperformed while pressing at least a portion near said butted portion atsaid joining-direction forward side of said first joining member (1)with respect to a probe inserted position and at least a portion nearsaid butted portion at said joining-direction forward side of saidsecond joining member (2) with respect to a probe inserted position fromsaid upper surface sides by said first forward pressing roller (11) andsaid second forward pressing roller (12), respectively.
 5. The frictionagitation joining method as recited in any one of claims 1 to 3, whereinsaid joining of said butted portion (3) is performed while pressing ajoined butted portion (3′) of said first and second joining members (1,2) from said upper surface sides by a third backward pressing roller(23) with a tapered periphery.
 6. The friction agitation joining methodas recited in claim 5, wherein said periphery of said third backwardpressing roller (23) is cooled.
 7. The friction agitation joining methodas recited in any one of claims 1 to 3, wherein said joining of saidbutted portion (3) is performed while cooling a lower surface of ajoined butted portion (3′) of said first and second joining members (1,2) by keeping a cooled periphery of a cooling roller (32) in contactwith said lower surface.
 8. The friction agitation joining method asrecited in claim 1 or 3, wherein said first forward pressing roller (11)and said second forward pressing roller (12) are separate members, andwherein said joining of said butted portion (3) is performed in a statein which an axis (P1, P2) of at least one of rollers including saidfirst forward pressing roller (11) and said second forward pressingroller (12) is inclined with respect to a butting direction (N) of saidjoining members (1, 2) within a plane perpendicular to a joiningdirection (WD).
 9. The friction agitation joining method as recited inclaim 1 or 3, wherein said first forward pressing roller (11) and saidsecond forward pressing roller (12) are separate members, and whereinsaid joining of said butted portion (3) is performed while changing atleast one of an inclination angle (β1) of an axis (P1) of said firstforward pressing roller (11) with respect to a butting direction (N) ofsaid first joining member (1) within a plane perpendicular to a joiningdirection (WD) and an inclination angle (β2) of an axis (P2) of saidsecond forward pressing roller (11) with respect to said buttingdirection (N) of said second joining member (2) within a planeperpendicular to a joining direction (WD) based on a measured value of acharacteristic concerning a joint state of a joined butted portion (3′)of said first and second joining members (1, 2).
 10. The frictionagitation joining method as recited in claim 1 or 3, wherein said firstforward pressing roller (11) and said second forward pressing roller(12) are separate members, and wherein said joining of said buttedportion (3) is performed in a state in which an axis (P1, P2) of atleast one of rollers including said first forward pressing roller (11)and said second forward pressing roller (12) is inclined with respect toa butting direction (N) of said joining members (1, 2) within a planeparallel to upper surfaces of said joining members (1, 2) so that forcein a butting direction (N) is given to said joining members (1, 2). 11.The friction agitation joining method as recited in any one of claims 1to 3, wherein said joining of said butted portion (3) is performed in astate in which said joining-direction forward sides of said firstjoining member (1) and said second joining member (2) with respect to aprobe inserted position is supported from lower surface sides thereof bya first forward supporting roller (31 a) and a second forward supportingroller (31 b) separated from said first forward supporting roller (31a), respectively, and an axis (S1, s2) of at least one of rollersincluding said first forward supporting roller (31 a) and said secondforward supporting roller (31 b) is inclined with respect to a buttingdirection (N) of said joining members (1, 2) within a plane parallel tolower surfaces of said joining members (1, 2) so that force in a buttingdirection (N) is given to said joining members (1, 2).
 12. The frictionagitation joining method as recited in any one of claims 1 to 3, whereinsaid joining of said butted portion (3) is performed in a state in whichsaid joining-direction backward sides of said first joining member (1)and said second joining member (2) with respect to a probe insertedposition is supported from lower surface sides thereof by a firstbackward supporting roller (32 a) and a second backward supportingroller (32 b) separated from said first backward supporting roller (32a), respectively.
 13. The friction agitation joining method as recitedin any one of claims 1 to 3, wherein said joining of said butted portion(3) is performed in a state in which tension in a direction parallel toa joining direction (WD) is given to at least one of said first joiningmember (1) and said second joining member (2).
 14. The frictionagitation joining method as recited in any one of claims 1 to 3, whereinsaid joining of said butted portion (3) is performed while heating alower surface of a probe inserted position of said butted portion (3) ora lower surface of a joining-direction forward side of said probeinserted position.
 15. The friction agitation joining method as recitedin any one of claims 1 to 3, wherein said joining of said butted portion(3) is performed while relatively moving said first and second joiningmembers (1, 2) with respect to a rotating sub-probe (47) of asub-joining tool (45) inserted into said butted portion (3) of saidfirst and second joining members (1, 2) or a joined butted portion (3′)from a lower surface side thereof so that said probe (42) and saidsub-probe (47) advance along said butted portion (3).
 16. A frictionagitation joining method for joining a first joining member (1) and asecond joining member (2) butted against each other by relatively movingsaid first and second joining members (1, 2) with respect to a rotatingprobe (42) of a joining tool (40) inserted into a butted portion (3) ofsaid first and second joining members (1, 2) from upper surface sidesthereof so that said probe (42) advances along said butted portion (3),wherein said joining of said butted portion (3) is performed whileheating a lower surface of a probe inserted position of said buttedportion (3) or a lower surface of a joining-direction forward side ofsaid probe inserted position.
 17. The friction agitation joining methodas recited in claim 16, wherein said heating is performed by heatconduction from a heated periphery of a backing roller (33) disposedopposite to said probe (42) at a lower surface side of said joiningmembers (1, 2).
 18. A friction agitation joining method for joining afirst joining member (1) and a second joining member (2) butted againsteach other with upper and lower surfaces being flush with each other byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromupper surface sides thereof so that said probe (42) advances along saidbutted portion (3), wherein said joining of said butted portion (3) isperformed while relatively moving said first and second joining members(1, 2) with respect to a rotating sub-probe (47) of a sub-joining tool(45) inserted into said butted portion (3) of said first and secondjoining members (1, 2) or a joined butted portion (3′) from a lowersurface side thereof so that said probe (42) and said sub-probe (47)advance along said butted portion (3).
 19. The friction agitationjoining method as recited in claim 18, wherein an insertion depth (δ) ofsaid sub-probe (47) is regulated within the range of from 0.1 to 0.5 mm.20. A method for manufacturing joined butted members by performing afriction agitation joining method for joining a first joining member (1)and a second joining member (2) butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingsaid first and second joining members (1, 2) with respect to a rotatingprobe (42) of a joining tool (40) inserted into a butted portion (3) ofsaid first and second joining members (1, 2) from said upper surfacesides so that said probe (42) advances along said butted portion (3),wherein joining of said butted portion (3) is performed while pressingjoining-direction forward sides of said first joining member (1) andsaid second joining member (2) with respect to a probe inserted positionfrom said upper surface sides by a first forward pressing roller (11)and a second forward pressing roller (11), respectively.
 21. A methodfor manufacturing joined butted member by performing a frictionagitation joining method for joining a first joining member (1) and asecond joining member (2) butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingsaid first and second joining members (1, 2) with respect to a rotatingprobe (42) of a joining tool (40) inserted into a butted portion (3) ofsaid first and second joining members (1, 2) from said upper surfacesides so that said probe (42) advances along said butted portion (3),wherein joining of said butted portion (3) is performed while pressingjoining-direction backward sides of said first joining member (1) andsaid second joining member (2) with respect to a probe inserted positionfrom said upper surface sides by a first backward pressing roller (21)and a second backward pressing roller (22), respectively.
 22. A methodfor manufacturing joined butted members by performing a frictionagitation joining method for joining a first joining member (1) and asecond joining member (2) butted against each other with a leveldifference formed at upper surface sides thereof by relatively movingsaid first and second joining members (1, 2) with respect to a rotatingprobe (42) of a joining tool (40) inserted into a butted portion (3) ofsaid first and second joining members (1, 2) from said upper surfacesides so that said probe (42) advances along said butted portion (3),wherein joining of said butted portion (3) is performed while pressingjoining-direction forward sides of said first joining member (1) andsaid second joining member (2) with respect to a probe inserted positionfrom said upper surface sides by a first forward pressing roller (11)and a second forward pressing roller (11), respectively, and pressingjoining-direction backward sides of said first joining member (1) andsaid second joining member (2) with respect to a probe inserted positionfrom said upper surface sides by a first backward pressing roller (21)and a second backward pressing roller (22), respectively.
 23. The methodfor manufacturing joined butted members as recited in any one of claims20 to 22, wherein said joining of said butted portion (3) is performedwhile heating a lower surface of a probe inserted position of saidbutted portion (3) or a lower surface of a joining-direction forwardside of said probe inserted position.
 24. The method for manufacturingjoined butted members as recited in any one of claims 20 to 22, whereinsaid joining of said butted portion (3) is performed while relativelymoving said first and second joining members (1, 2) with respect to arotating sub-probe (47) of a sub-joining tool (45) inserted into saidbutted portion (3) of said first and second joining members (1, 2) or ajoined butted portion (3′) from a lower surface side thereof so thatsaid probe (42) and said sub-probe (47) advance along said buttedportion (3).
 25. A method for manufacturing joined butted members byperforming a friction agitation joining method for joining a firstjoining member (1) and a second joining member (2) butted against eachother by relatively moving said first and second joining members (1, 2)with respect to a rotating probe (42) of a joining tool (40) insertedinto a butted portion (3) of said first and second joining members (1,2) from upper surface sides thereof so that said probe (42) advancesalong said butted portion (3), wherein said joining of said buttedportion (3) is performed while heating a lower surface of a probeinserted position of said butted portion (3) or a lower surface of ajoining-direction forward side of said probe inserted position.
 26. Amethod for manufacturing joined butted members by performing a frictionagitation joining method for joining a first joining member (1) and asecond joining member (2) butted against each other with upper and lowersurfaces being flush with each other by relatively moving said first andsecond joining members (1, 2) with respect to a rotating probe (42) of ajoining tool (40) inserted into a butted portion (3) of said first andsecond joining members (1, 2) from upper surface sides thereof so thatsaid probe (42) advances along said butted portion (3), wherein saidjoining of said butted portion (3) is performed while relatively movingsaid first and second joining members (1, 2) with respect to a rotatingsub-probe (47) of a sub-joining tool (45) inserted into said buttedportion (3) of said first and second joining members (1, 2) or a joinedbutted portion (3′) from a lower surface side thereof so that said probe(42) and said sub-probe (47) advance along said butted portion (3). 27.A friction agitation joining apparatus for joining a first joiningmember (1) and a second joining member (2) butted against each otherwith a level difference formed at upper surface sides thereof byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), comprising: a first forward pressing roller (11) forpressing joining-direction forward side of said first joining member (1)with respect to a probe inserted position from upper surface sidethereof; and a second forward pressing roller (12) for pressingjoining-direction forward side of said second joining member (2) withrespect to said probe inserted position from upper surface side thereof.28. A friction agitation joining apparatus (80) for joining a firstjoining member (1) and a second joining member (2) butted against eachother with a level difference formed at upper surface sides thereof byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), comprising: a first backward pressing roller (21)for pressing joining-direction backward side of said first joiningmember (1) with respect to a probe inserted position from upper surfaceside thereof; and a second backward pressing roller (22) for pressingjoining-direction backward side of said second joining member (2) withrespect to said probe inserted position from upper surface side thereof.29. A friction agitation joining apparatus (80) for joining a firstjoining member (1) and a second joining member (2) butted against eachother with a level difference formed at upper surface sides thereof byrelatively moving said first and second joining members (1, 2) withrespect to a rotating probe (42) of a joining tool (40) inserted into abutted portion (3) of said first and second joining members (1, 2) fromsaid upper surface sides so that said probe (42) advances along saidbutted portion (3), comprising: a first forward pressing roller (11) forpressing joining-direction forward side of said first joining member (1)with respect to a probe inserted position from upper surface sidethereof; a second forward pressing roller (12) for pressingjoining-direction forward side of said second joining member (2) withrespect to said probe inserted position from upper surface side thereof;a first backward pressing roller (21) for pressing joining-directionbackward side of said first joining member (1) with respect to a probeinserted position from upper surface side thereof; and a second backwardpressing roller (22) for pressing joining-direction backward side ofsaid second joining member (2) with respect to said probe insertedposition from upper surface side thereof.
 30. The friction agitationjoining apparatus as recited in any one of claims 27 to 29, furthercomprising a third backward pressing roller (23) having a taperedperiphery for pressing a joined butted portion (3′) of said joiningmembers (1, 2) from surface sides thereof.
 31. The friction agitationjoining apparatus as recited in claim 30, wherein said periphery of saidthird backward pressing roller (23) is cooled.
 32. The frictionagitation joining apparatus as recited in any one of claims 27 to 29,further comprising a cooling roller (32) for cooling a lower surface ofa joined butted portion (3′) of said first and second joining members(1, 2) by keeping a cooled periphery of said cooling roller (32) incontact with said lower surface.
 33. The friction agitation joiningapparatus as recited in claim 27 or 29, wherein said first forwardpressing roller (11) and said second forward pressing roller (12) areseparate members, and further comprising an inclination angle changingapparatus (60 a, 60 b) for changing an inclination angle (β1, β2) of anaxis (P1, P2) of at least one of rollers including said first forwardpressing roller (11) and said second forward pressing roller (12) withrespect to a butting direction (N) of the joining members within a planeperpendicular to a joining direction (WD).
 34. The friction agitationjoining apparatus as recited in claim 33, further comprising: ameasuring device (50) for measuring a characteristic concerning a jointstate of a joined butted portion (3′) of said joining members; and acontroller (61 a, 61 a) for controls an operation of said inclinationangle changing apparatus (60 a, 60 b) based on a measured value obtainedby said measuring device (50).
 35. The friction agitation joiningapparatus as recited in claim 27 or 29, wherein said first forwardpressing roller (11) and said second forward pressing roller (12) areseparate members, and further comprising an inclination angle changingapparatus (60 a, 60 b) for changing an inclination angle (α1, α2) of anaxis (P1, P2) of at least one of rollers including said first forwardpressing roller (11) and said second forward pressing roller (12) withrespect to a butting direction (N) of the joining members within a planeparallel to upper surfaces of said joining members.
 36. The frictionagitation joining apparatus as recited in claim 35, further comprising:a measuring device (50) for measuring a characteristic concerning ajoint state of a joined butted portion (3′) of said joining members; anda controller (61 a, 61 a) for controls an operation of said inclinationangle changing apparatus (60 a, 60 b) based on a measured value obtainedby said measuring device (50).
 37. The friction agitation joiningapparatus as recited in any one of claims 27 to 29, further comprising:a first forward supporting roller (31 a) for supporting saidjoining-direction forward side of said first joining member (1) withrespect to a probe inserted position from a lower surface side thereof;a second forward supporting roller (31 b) for supporting saidjoining-direction forward side of said second joining member (2) withrespect to a probe inserted position from a lower surface side thereof,said second forward supporting roller (31 b) being separated from saidfirst forward supporting roller (31 a); and an inclination anglechanging apparatus (65 a, 65 b) for changing an inclination angle (γ1,γ2) of an axis (S1, S2) of at least one of rollers including said firstforward supporting roller (31 a) and said second forward supportingroller (31 b) with respect to a butting direction (N) of the joiningmembers within a plane parallel to lower surfaces of said joiningmembers.
 38. The friction agitation joining apparatus as recited in anyone of claims 27 to 29, further comprising: a first backward supportingroller (32 a) for supporting said joining-direction backward side ofsaid first joining member (1) with respect to a probe inserted positionfrom a lower surface side thereof; and a second backward supportingroller (32 b) for supporting said joining-direction forward side of saidsecond joining member (2) with respect to a probe inserted position froma lower surface side thereof, said second backward supporting roller (32b) being separated from said first backward supporting roller (32 a).39. The friction agitation joining apparatus as recited in any one ofclaims 27 to 29, further comprising a tension device for giving tensionin a direction parallel to a joining direction (WD) to at least one ofsaid first joining member (1) and said second joining member (2). 40.The friction agitation joining apparatus as recited in any one of claims27 to 29, further comprising a heating device (91, 92, 93) for heating alower surface of a probe inserted position of said butted portion (3) ora lower surface of a joining-direction forward side of said probeinserted position.
 41. The friction agitation joining apparatus asrecited in any one of claims 27 to 29, further comprising a sub-joiningtool (45) having a rotatable sub-probe (47), wherein said rotatingsub-probe (47) is inserted into said butted portion (3) or a joinedbutted portion (3′) when said butted portion (3) is joined or is beingjoined to join a root remaining portion (R) produced at said joinedbutted portion (3′) of said joining members (1, 2).
 42. A frictionagitation joining apparatus (80) for joining a first joining member (1)and a second joining member (2) butted against each other by relativelymoving said first and second joining members (1, 2) with respect to arotating probe (42) of a joining tool (40) inserted into a buttedportion (3) of said first and second joining members (1, 2) from saidupper surface sides so that said probe (42) advances along said buttedportion (3), comprising: a heating device (91, 92, 93) for heating alower surface of a probe inserted position of said butted portion (3) ora lower surface of a joining-direction forward side of said probeinserted position.
 43. A friction agitation joining apparatus (80) forjoining a first joining member (1) and a second joining member (2)butted against each other with upper and lower surfaces being flush witheach other by relatively moving said first and second joining members(1, 2) with respect to a rotating probe (42) of a joining tool (40)inserted into a butted portion (3) of said first and second joiningmembers (1, 2) from upper surface sides thereof so that said probe (42)advances along said butted portion (3), comprising: a sub-joining tool(45) having a rotatable sub-probe (47), wherein said rotating sub-probe(47) is inserted into said butted portion (3) or a joined butted portion(3′) when said butted portion (3) is joined or is being joined to join aroot remaining portion (R) produced at said joined butted portion (3′)of said joining members (1, 2).